如果 'arr[i]' 是 'j'，则重新排列一个数组，使得 'arr[j]' 变为 'i' |设置 1

如果 'arr[i]' 是 'j'，则重新排列一个数组，使得 'arr[j]' 变为 'i' |设置 1

给定一个大小为 n 的数组，其中所有元素都是不同的，并且范围从 0 到 n-1，更改 arr[] 的内容，使 arr[i] = j 更改为 arr[j] = i。
例子：

Example 1:
Input: arr[]  = {1, 3, 0, 2};
Output: arr[] = {2, 0, 3, 1};
Explanation for the above output.
Since arr[0] is 1, arr[1] is changed to 0
Since arr[1] is 3, arr[3] is changed to 1
Since arr[2] is 0, arr[0] is changed to 2
Since arr[3] is 2, arr[2] is changed to 3

Example 2:
Input: arr[]  = {2, 0, 1, 4, 5, 3};
Output: arr[] = {1, 2, 0, 5, 3, 4};

Example 3:
Input: arr[]  = {0, 1, 2, 3};
Output: arr[] = {0, 1, 2, 3};

Example 4:
Input: arr[]  = {3, 2, 1, 0};
Output: arr[] = {3, 2, 1, 0};

一个简单的解决方案是创建一个临时数组，并将“i”一个一个复制到“temp[arr[i]]”，其中 i 从 0 变化到 n-1。
下面是上述思想的实现。

C++

// A simple C++ program to rearrange contents of arr[]
// such that arr[j] becomes j if arr[i] is j
#include 
using namespace std;
 
// A simple method to rearrange 'arr[0..n-1]' so that 'arr[j]'
// becomes 'i' if 'arr[i]' is 'j'
void rearrangeNaive(int arr[], int n)
{
    // Create an auxiliary array of same size
    int temp[n], i;
 
    // Store result in temp[]
    for (i = 0; i < n; i++)
        temp[arr[i]] = i;
 
    // Copy temp back to arr[]
    for (i = 0; i < n; i++)
        arr[i] = temp[i];
}
 
// A utility function to print contents of arr[0..n-1]
void printArray(int arr[], int n)
{
    int i;
    for (i = 0; i < n; i++)
        cout << ("%d ", arr[i]);
    cout << ("\n");
}
 
// Driver code
int main()
{
    int arr[] = { 1, 3, 0, 2 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    cout << ("Given array is \n");
    printArray(arr, n);
 
    rearrangeNaive(arr, n);
 
    cout << ("Modified array is \n");
    printArray(arr, n);
    return 0;
}
 
// This code is contributed by Code_Mech

C

// A simple C program to rearrange contents of arr[]
// such that arr[j] becomes j if arr[i] is j
#include 
 
// A simple method to rearrange 'arr[0..n-1]' so that 'arr[j]'
// becomes 'i' if 'arr[i]' is 'j'
void rearrangeNaive(int arr[], int n)
{
    // Create an auxiliary array of same size
    int temp[n], i;
 
    // Store result in temp[]
    for (i = 0; i < n; i++)
        temp[arr[i]] = i;
 
    // Copy temp back to arr[]
    for (i = 0; i < n; i++)
        arr[i] = temp[i];
}
 
// A utility function to print contents of arr[0..n-1]
void printArray(int arr[], int n)
{
    int i;
    for (i = 0; i < n; i++)
        printf("%d ", arr[i]);
    printf("\n");
}
 
// Driver program
int main()
{
    int arr[] = { 1, 3, 0, 2 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    printf("Given array is \n");
    printArray(arr, n);
 
    rearrangeNaive(arr, n);
 
    printf("Modified array is \n");
    printArray(arr, n);
    return 0;
}

Java

// A simple Java program to rearrange contents of arr[]
// such that arr[j] becomes j if arr[i] is j
class RearrangeArray {
    // A simple method to rearrange 'arr[0..n-1]' so that 'arr[j]'
    // becomes 'i' if 'arr[i]' is 'j'
    void rearrangeNaive(int arr[], int n)
    {
        // Create an auxiliary array of same size
        int temp[] = new int[n];
        int i;
 
        // Store result in temp[]
        for (i = 0; i < n; i++)
            temp[arr[i]] = i;
 
        // Copy temp back to arr[]
        for (i = 0; i < n; i++)
            arr[i] = temp[i];
    }
 
    // A utility function to print contents of arr[0..n-1]
    void printArray(int arr[], int n)
    {
        int i;
        for (i = 0; i < n; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println("");
    }
 
    // Driver program to test above functions
    public static void main(String[] args)
    {
        RearrangeArray arrange = new RearrangeArray();
        int arr[] = { 1, 3, 0, 2 };
        int n = arr.length;
 
        System.out.println("Given array is ");
        arrange.printArray(arr, n);
 
        arrange.rearrangeNaive(arr, n);
 
        System.out.println("Modified array is ");
        arrange.printArray(arr, n);
    }
}

Python3

# A simple Python3 program to rearrange
# contents of arr[] such that arr[j]
# becomes j if arr[i] is j
 
# A simple method to rearrange
# 'arr[0..n-1]' so that 'arr[j]'
# becomes 'i' if 'arr[i]' is 'j'
def rearrangeNaive(arr, n):
 
    # Create an auxiliary array
    # of same size
    temp = [0] * n
     
    # Store result in temp[]
    for i in range(0, n):
        temp[arr[i]] = i
 
    # Copy temp back to arr[]
    for i in range(0, n):
        arr[i] = temp[i]
 
 
    # A utility function to print
    # contents of arr[0..n-1]
def printArray(arr, n):
    for i in range(0, n):
        print(arr[i], end = " ")
 
# Driver program
arr = [1, 3, 0, 2]
n = len(arr)
print("Given array is", end = " ")
printArray(arr, n)
 
rearrangeNaive(arr, n)
print("\nModified array is", end = " ")
printArray(arr, n)
 
# This code is contributed by Smitha Dinesh Semwal

C#

// A simple C# program to rearrange contents of arr[]
// such that arr[j] becomes j if arr[i] is j
 
using System;
class RearrangeArray {
    // A simple method to rearrange 'arr[0..n-1]' so that 'arr[j]'
    // becomes 'i' if 'arr[i]' is 'j'
    void rearrangeNaive(int[] arr, int n)
    {
        // Create an auxiliary array of same size
        int[] temp = new int[n];
        int i;
 
        // Store result in temp[]
        for (i = 0; i < n; i++)
            temp[arr[i]] = i;
 
        // Copy temp back to arr[]
        for (i = 0; i < n; i++)
            arr[i] = temp[i];
    }
 
    // A utility function to print contents of arr[0..n-1]
    void printArray(int[] arr, int n)
    {
        int i;
        for (i = 0; i < n; i++) {
            Console.Write(arr[i] + " ");
        }
        Console.WriteLine("");
    }
 
    // Driver program to test above functions
    public static void Main()
    {
        RearrangeArray arrange = new RearrangeArray();
        int[] arr = { 1, 3, 0, 2 };
        int n = arr.Length;
 
        Console.WriteLine("Given array is ");
        arrange.printArray(arr, n);
 
        arrange.rearrangeNaive(arr, n);
 
        Console.WriteLine("Modified array is ");
        arrange.printArray(arr, n);
    }
}

Javascript

 
// A simple JavaScript program to rearrange contents of arr[]
// such that arr[j] becomes j if arr[i] is j
 
// A simple method to rearrange 'arr[0..n-1]' so that 'arr[j]'
// becomes 'i' if 'arr[i]' is 'j'
function rearrangeNaive(arr, n)
{
    // Create an auxiliary array of same size
    let temp = new Array(n), i;
 
    // Store result in temp[]
    for (i = 0; i < n; i++)
        temp[arr[i]] = i;
 
    // Copy temp back to arr[]
    for (i = 0; i < n; i++)
        arr[i] = temp[i];
}
 
// A utility function to print contents of arr[0..n-1]
function printArray(arr, n)
{
    let i;
    for (i = 0; i < n; i++)
        document.write(" " + arr[i]);
    document.write("<br>");
}
 
// Driver code
    let arr = [ 1, 3, 0, 2 ];
    let n = arr.length;
 
    document.write("Given array is <br>");
    printArray(arr, n);
 
    rearrangeNaive(arr, n);
 
    document.write("Modified array is <br>");
    printArray(arr, n);
 
// This code is contributed by Surbhi Tyagi.
 

输出：

Given array is
1 3 0 2
Modified array is
2 0 3 1

时间复杂度： O(n)

辅助空间： O(n)

我们可以在 O(n) 时间和 O(1) 辅助空间内解决这个问题吗？
这个想法是基于这样一个事实，即修改后的数组基本上是输入数组的排列。我们可以通过在更新前存储下一项来找到目标排列。
让我们以数组 '{1, 3, 0, 2}' 为例。我们从 i = 0 开始，arr[i] 为 1。所以我们转到 arr[1] 并将其更改为 0（因为 i 为 0）。在进行更改之前，我们存储 arr[1] 的旧值，因为旧值将成为我们的新索引 i。在下一次迭代中，我们有 i = 3，arr[3] 为 2，因此我们将 arr[2] 更改为 3。在进行更改之前，我们将下一个 i 存储为 arr[2] 的旧值。
下面的代码给出了关于这种方法的想法。

// This function works only when output is a permutation
// with one cycle.
void rearrangeUtil(int arr[], int n)
{
    // 'val' is the value to be stored at 'arr[i]'
    int val = 0;   // The next value is determined
                  // using current index
    int i = arr[0];  // The next index is determined
                     // using current value

    // While all elements in cycle are not processed
    while (i != 0)
    {
        // Store value at index as it is going to be
        // used as next index
        int new_i = arr[i];

        // Update arr[]
        arr[i] = val;

        // Update value and index for next iteration
        val = i;
        i = new_i;
    }

    arr[0] = val;  // Update the value at arr[0]
}

上述函数不适用于 {2, 0, 1, 4, 5, 3} 等输入；因为有两个周期。一个周期是 (2, 0, 1)，另一个周期是 (4, 5, 3)。
如何处理具有 O(1) 空间约束的多个周期？
这个想法是一个一个地处理所有周期。为了检查一个元素是否被处理，我们将已处理项 arr[i] 的值更改为 -arr[i]。由于 0 不能为负数，我们首先将所有 arr[i] 更改为 arr[i] + 1。最后，我们将所有值设为正数并减去 1 以取回旧值。

C++

// A space efficient C++ program to rearrange contents of
// arr[] such that arr[j] becomes j if arr[i] is j
#include 
using namespace std;
 
// A utility function to rearrange elements in the cycle
// starting at arr[i]. This function assumes values in
// arr[] be from 1 to n. It changes arr[j-1] to i+1
// if arr[i-1] is j+1
void rearrangeUtil(int arr[], int n, int i)
{
    // 'val' is the value to be stored at 'arr[i]'
    int val = -(i + 1); // The next value is determined
    // using current index
    i = arr[i] - 1; // The next index is determined
    // using current value
 
    // While all elements in cycle are not processed
    while (arr[i] > 0)
    {
         
        // Store value at index as it is going to be
        // used as next index
        int new_i = arr[i] - 1;
 
        // Update arr[]
        arr[i] = val;
 
        // Update value and index for next iteration
        val = -(i + 1);
        i = new_i;
    }
}
 
// A space efficient method to rearrange 'arr[0..n-1]'
// so that 'arr[j]' becomes 'i' if 'arr[i]' is 'j'
void rearrange(int arr[], int n)
{
    // Increment all values by 1, so that all elements
    // can be made negative to mark them as visited
    int i;
    for (i = 0; i < n; i++)
        arr[i]++;
 
    // Process all cycles
    for (i = 0; i < n; i++)
    {
         
        // Process cycle starting at arr[i] if this cycle is
        // not already processed
        if (arr[i] > 0)
            rearrangeUtil(arr, n, i);
    }
 
    // Change sign and values of arr[] to get the original
    // values back, i.e., values in range from 0 to n-1
    for (i = 0; i < n; i++)
        arr[i] = (-arr[i]) - 1;
}
 
// A utility function to print contents of arr[0..n-1]
void printArray(int arr[], int n)
{
    int i;
    for (i = 0; i < n; i++)
        cout << arr[i] << " ";
    cout << endl;
}
 
// Driver program
int main()
{
    int arr[] = { 2, 0, 1, 4, 5, 3 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    cout << "Given array is " << endl;
    printArray(arr, n);
 
    rearrange(arr, n);
 
    cout << "Modified array is " << endl;
    printArray(arr, n);
    return 0;
}
 
// This code is contributed by shubhamsingh10

C

// A space efficient C program to rearrange contents of
// arr[] such that arr[j] becomes j if arr[i] is j
#include 
 
// A utility function to rearrange elements in the cycle
// starting at arr[i]. This function assumes values in
// arr[] be from 1 to n.  It changes arr[j-1] to i+1
// if arr[i-1] is j+1
void rearrangeUtil(int arr[], int n, int i)
{
    // 'val' is the value to be stored at 'arr[i]'
    int val = -(i + 1); // The next value is determined
    // using current index
    i = arr[i] - 1; // The next index is determined
    // using current value
 
    // While all elements in cycle are not processed
    while (arr[i] > 0) {
        // Store value at index as it is going to be
        // used as next index
        int new_i = arr[i] - 1;
 
        // Update arr[]
        arr[i] = val;
 
        // Update value and index for next iteration
        val = -(i + 1);
        i = new_i;
    }
}
 
// A space efficient method to rearrange 'arr[0..n-1]'
// so that 'arr[j]' becomes 'i' if 'arr[i]' is 'j'
void rearrange(int arr[], int n)
{
    // Increment all values by 1, so that all elements
    // can be made negative to mark them as visited
    int i;
    for (i = 0; i < n; i++)
        arr[i]++;
 
    // Process all cycles
    for (i = 0; i < n; i++) {
        // Process cycle starting at arr[i] if this cycle is
        // not already processed
        if (arr[i] > 0)
            rearrangeUtil(arr, n, i);
    }
 
    // Change sign and values of arr[] to get the original
    // values back, i.e., values in range from 0 to n-1
    for (i = 0; i < n; i++)
        arr[i] = (-arr[i]) - 1;
}
 
// A utility function to print contents of arr[0..n-1]
void printArray(int arr[], int n)
{
    int i;
    for (i = 0; i < n; i++)
        printf("%d ", arr[i]);
    printf("\n");
}
 
// Driver program
int main()
{
    int arr[] = { 2, 0, 1, 4, 5, 3 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    printf("Given array is \n");
    printArray(arr, n);
 
    rearrange(arr, n);
 
    printf("Modified array is \n");
    printArray(arr, n);
    return 0;
}

Java

// A space efficient Java program to rearrange contents of
// arr[] such that arr[j] becomes j if arr[i] is j
 
class RearrangeArray {
    // A utility function to rearrange elements in the cycle
    // starting at arr[i]. This function assumes values in
    // arr[] be from 1 to n.  It changes arr[j-1] to i+1
    // if arr[i-1] is j+1
    void rearrangeUtil(int arr[], int n, int i)
    {
        // 'val' is the value to be stored at 'arr[i]'
 
        // The next value is determined using current index
        int val = -(i + 1);
 
        // The next index is determined
        // using current value
        i = arr[i] - 1;
 
        // While all elements in cycle are not processed
        while (arr[i] > 0) {
            // Store value at index as it is going to be
            // used as next index
            int new_i = arr[i] - 1;
 
            // Update arr[]
            arr[i] = val;
 
            // Update value and index for next iteration
            val = -(i + 1);
            i = new_i;
        }
    }
 
    // A space efficient method to rearrange 'arr[0..n-1]'
    // so that 'arr[j]' becomes 'i' if 'arr[i]' is 'j'
    void rearrange(int arr[], int n)
    {
        // Increment all values by 1, so that all elements
        // can be made negative to mark them as visited
        int i;
        for (i = 0; i < n; i++)
            arr[i]++;
 
        // Process all cycles
        for (i = 0; i < n; i++) {
            // Process cycle starting at arr[i] if this cycle is
            // not already processed
            if (arr[i] > 0)
                rearrangeUtil(arr, n, i);
        }
 
        // Change sign and values of arr[] to get the original
        // values back, i.e., values in range from 0 to n-1
        for (i = 0; i < n; i++)
            arr[i] = (-arr[i]) - 1;
    }
 
    // A utility function to print contents of arr[0..n-1]
    void printArray(int arr[], int n)
    {
        int i;
        for (i = 0; i < n; i++)
            System.out.print(arr[i] + " ");
        System.out.println("");
    }
 
    // Driver program
    public static void main(String[] args)
    {
        RearrangeArray arrange = new RearrangeArray();
        int arr[] = { 2, 0, 1, 4, 5, 3 };
        int n = arr.length;
 
        System.out.println("Given array is ");
        arrange.printArray(arr, n);
 
        arrange.rearrange(arr, n);
 
        System.out.println("Modified array is ");
        arrange.printArray(arr, n);
    }
}

Python3

# A space efficient Python3 program to
# rearrange contents of arr such that
# arr[j] becomes j if arr[i] is j
 
# A utility function to rearrange elements
# in the cycle starting at arr[i]. This
# function assumes values in arr be from
# 1 to n. It changes arr[j-1] to i+1 if
# arr[i-1] is j+1
def rearrangeUtil(arr, n, i):
     
    # 'val' is the value to be stored at 
    # 'arr[i]'
    # The next value is determined using
    # current index 
    val = -(i + 1)
     
    # The next index is determined using
    # current index
    i = arr[i] - 1
  
    # While all elements in cycle are
    # not processed
    while (arr[i] > 0):
         
        # Store value at index as it is
        # going to be used as next index
        new_i = arr[i] - 1
         
        # Update arr
        arr[i] = val
         
        # Update value and index for
        # next iteration
        val = -(i + 1)
        i = new_i
 
# A space efficient method to rearrange
# 'arr[0..n-1]' so that 'arr[j]' becomes
# 'i' if 'arr[i]' is 'j'
def rearrange(arr, n):
     
    # Increment all values by 1, so that
    # all elements can be made negative to
    # mark them as visited
    for i in range(n):
        arr[i] += 1
         
    # Process all cycles
    for i in range(n):
         
        # Process cycle starting at arr[i] if 
        # this cycle is not already processed
        if (arr[i] > 0):
            rearrangeUtil(arr, n, i)
     
    # Change sign and values of arr to
    # get the original values back, i.e., 
    # values in range from 0 to n-1
    for i in range(n):
        arr[i] = (-arr[i]) - 1
 
# A utility function to print contents o
# f arr[0..n-1]
def printArray(arr, n):
     
    for i in range(n):
        print(arr[i], end = " ")
    print()
 
# Driver code
arr = [ 2, 0, 1, 4, 5, 3 ]
n = len(arr)
 
print("Given array is ")
printArray(arr, n)
 
rearrange(arr, n)
 
print("Modified array is ")
printArray(arr, n)
 
# This code is contributed by shubhamsingh10

C＃

// A simple C# program to
// rearrange contents of arr[]
// such that arr[j] becomes
// j if arr[i] is j
using System;
 
class GFG {
    // A simple method to rearrange
    // 'arr[0..n-1]' so that 'arr[j]'
    // becomes 'i' if 'arr[i]' is 'j'
    void rearrangeNaive(int[] arr,
                        int n)
    {
        // Create an auxiliary
        // array of same size
        int[] temp = new int[n];
        int i;
 
        // Store result in temp[]
        for (i = 0; i < n; i++)
            temp[arr[i]] = i;
 
        // Copy temp back to arr[]
        for (i = 0; i < n; i++)
            arr[i] = temp[i];
    }
 
    // A utility function to
    // print contents of arr[0..n-1]
    void printArray(int[] arr, int n)
    {
        int i;
        for (i = 0; i < n; i++) {
            Console.Write(arr[i] + " ");
        }
        Console.WriteLine("");
    }
 
    // Driver Code
    public static void Main()
    {
        GFG arrange = new GFG();
        int[] arr = { 2, 0, 1, 4, 5, 3 };
        int n = arr.Length;
 
        Console.WriteLine("Given array is ");
        arrange.printArray(arr, n);
 
        arrange.rearrangeNaive(arr, n);
 
        Console.WriteLine("Modified array is ");
        arrange.printArray(arr, n);
    }
}
 
// This code is contributed by anuj_67.

Javascript

 
// A space efficient Javascript program to rearrange contents of
// arr[] such that arr[j] becomes j if arr[i] is j
 
     
    // A utility function to rearrange elements in the cycle
    // starting at arr[i]. This function assumes values in
    // arr[] be from 1 to n.  It changes arr[j-1] to i+1
    // if arr[i-1] is j+1
    function rearrangeUtil(arr,n,i)
    {
        // 'val' is the value to be stored at 'arr[i]'
  
        // The next value is determined using current index
        let val = -(i + 1);
  
        // The next index is determined
        // using current value
        i = arr[i] - 1;
  
        // While all elements in cycle are not processed
        while (arr[i] > 0) {
            // Store value at index as it is going to be
            // used as next index
            let new_i = arr[i] - 1;
  
            // Update arr[]
            arr[i] = val;
  
            // Update value and index for next iteration
            val = -(i + 1);
            i = new_i;
        }
    }
     
    // A space efficient method to rearrange 'arr[0..n-1]'
    // so that 'arr[j]' becomes 'i' if 'arr[i]' is 'j'
    function rearrange(arr,n)
    {
        // Increment all values by 1, so that all elements
        // can be made negative to mark them as visited
        let i;
        for (i = 0; i < n; i++)
            arr[i]++;
  
        // Process all cycles
        for (i = 0; i < n; i++) {
            // Process cycle starting at arr[i] if this cycle is
            // not already processed
            if (arr[i] > 0)
                rearrangeUtil(arr, n, i);
        }
  
        // Change sign and values of arr[] to get the original
        // values back, i.e., values in range from 0 to n-1
        for (i = 0; i < n; i++)
            arr[i] = (-arr[i]) - 1;
    }
     
    // A utility function to print contents of arr[0..n-1]
    function printArray(arr,n)
    {
        let i;
        for (i = 0; i < n; i++)
            document.write(arr[i] + " ");
        document.write("<br>");
    }
     
    // Driver program
     
    let arr=[2, 0, 1, 4, 5, 3];
    let n = arr.length;
     
    document.write("Given array is <br>");
    printArray(arr, n);
     
    rearrange(arr, n);
    document.write("Modified array is <br>");
    printArray(arr, n);
     
    // This code is contributed by rag2127
     

输出：

Given array is
2 0 1 4 5 3
Modified array is
1 2 0 5 3 4 

乍一看，这种方法的时间复杂度似乎超过了 O(n)。如果我们仔细观察，我们会注意到没有元素被处理超过固定次数。
另一种方法：这个想法是将每个元素的新值和旧值分别存储为 n 的商和余数（n 是数组的大小）。
例如，假设一个元素的新值为 2，旧值为 1，n 为 3，则该元素的值存储为 1 + 2*3 = 7。我们可以通过 7%3 = 1 和它的7/3 = 2 的新值。
感谢 Prateek Oraon 提出这种方法。

C++

// A simple C++ program to rearrange
// contents of arr[] such that arr[j]
// becomes j if arr[i] is j
#include 
using namespace std;
 
// A simple method to rearrange
// 'arr[0..n-1]' so that 'arr[j]'
// becomes 'i' if 'arr[i]' is 'j'
void rearrange(int arr[], int n)
{
    for (int i = 0; i < n; i++) {
 
        // retrieving old value and
        // storing with the new one
        arr[arr[i] % n] += i * n;
    }
 
    for (int i = 0; i < n; i++) {
 
        // retrieving new value
        arr[i] /= n;
    }
}
 
// A utility function to print
// contents of arr[0..n-1]
void printArray(int arr[], int n)
{
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";
 
    cout << endl;
}
 
// Driver program
int main()
{
    int arr[] = { 2, 0, 1, 4, 5, 3 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    cout << "Given array is : " << endl;
    printArray(arr, n);
 
    rearrange(arr, n);
 
    cout << "Modified array is :" << endl;
    printArray(arr, n);
 
    return 0;
}

Java

// A simple JAVA program to rearrange
// contents of arr[] such that arr[j]
// becomes j if arr[i] is j
 
class GFG {
 
    // A simple method to rearrange
    // 'arr[0..n-1]' so that 'arr[j]'
    // becomes 'i' if 'arr[i]' is 'j'
    static void rearrange(int arr[], int n)
    {
        for (int i = 0; i < n; i++) {
 
            // retrieving old value and
            // storing with the new one
            arr[arr[i] % n] += i * n;
        }
 
        for (int i = 0; i < n; i++) {
 
            // retrieving new value
            arr[i] /= n;
        }
    }
 
    // A utility function to print
    // contents of arr[0..n-1]
    static void printArray(int arr[], int n)
    {
        for (int i = 0; i < n; i++) {
            System.out.print(arr[i] + " ");
        }
 
        System.out.println();
    }
 
    // Driver code
    public static void main(String[] args)
    {
        int arr[] = { 2, 0, 1, 4, 5, 3 };
        int n = arr.length;
 
        System.out.println("Given array is : ");
        printArray(arr, n);
 
        rearrange(arr, n);
 
        System.out.println("Modified array is :");
        printArray(arr, n);
    }
}
 
// This code has been contributed by 29AjayKumar

Python3

# A simple Python3 program to rearrange
# contents of arr[] such that arr[j]
# becomes j if arr[i] is j
 
# A simple method to rearrange
# 'arr[0..n-1]' so that 'arr[j]'
# becomes 'i' if 'arr[i]' is 'j'
def rearrange(arr, n):
     
    for i in range(n):
         
        # Retrieving old value and
        # storing with the new one
        arr[arr[i] % n] += i * n
     
    for i in range(n):
         
        # Retrieving new value
        arr[i] //= n
     
# A utility function to pr
# contents of arr[0..n-1]
def printArray(arr, n):
     
    for i in range(n):
        print(arr[i], end = " ")
    print()
 
# Driver code
arr = [2, 0, 1, 4, 5, 3]
n = len(arr)
 
print("Given array is : ")
printArray(arr, n)
 
rearrange(arr, n)
 
print("Modified array is :")
printArray(arr, n)
 
# This code is contributed by shubhamsingh10

C＃

// A simple C# program to rearrange
// contents of arr[] such that arr[j]
// becomes j if arr[i] is j
using System;
 
class GFG{
 
    // A simple method to rearrange
    // 'arr[0..n-1]' so that 'arr[j]'
    // becomes 'i' if 'arr[i]' is 'j'
    static void rearrange(int[] arr, int n)
    {
        for (int i = 0; i < n; i++) {
     
            // retrieving old value and
            // storing with the new one
            arr[arr[i] % n] += i * n;
        }
     
        for (int i = 0; i < n; i++) {
     
            // retrieving new value
            arr[i] /= n;
        }
    }
     
    // A utility function to print
    // contents of arr[0..n-1]
    static void printArray(int[] arr, int n)
    {
        for (int i = 0; i < n; i++)
            Console.Write(arr[i] + " ");
     
        Console.WriteLine();
    }
     
    // Driver program
    static public void Main ()
    {
        int[] arr = { 2, 0, 1, 4, 5, 3 };
        int n = arr.Length;
     
        Console.WriteLine("Given array is : ");
        printArray(arr, n);
     
        rearrange(arr, n);
     
        Console.WriteLine("Modified array is :");
        printArray(arr, n);
    }
}
 
// This code is contributed by shubhamsingh10

Javascript

 
// A simple javascript program to rearrange
// contents of arr such that arr[j]
// becomes j if arr[i] is j
 
 
// A simple method to rearrange
// 'arr[0..n-1]' so that 'arr[j]'
// becomes 'i' if 'arr[i]' is 'j'
function rearrange(arr , n)
{
    for (i = 0; i < n; i++) {
 
        // retrieving old value and
        // storing with the new one
        arr[arr[i] % n] += i * n;
    }
 
    for (i = 0; i < n; i++) {
 
        // retrieving new value
        arr[i] = parseInt(arr[i]/n);
    }
}
 
// A utility function to print
// contents of arr[0..n-1]
function printArray(arr , n)
{
    for (i = 0; i < n; i++) {
        document.write(arr[i] + " ");
    }
 
    document.write();
}
 
// Driver code
var arr = [ 2, 0, 1, 4, 5, 3 ];
var n = arr.length;
 
document.write("Given array is : " + "<br>");
printArray(arr, n);
 
rearrange(arr, n);
document.write("<br>")
 
document.write("Modified array is : " + "<br>");
printArray(arr, n);
 
// This code contributed by Rajput-Ji
 

输出：

Given array is : 
2 0 1 4 5 3 
Modified array is :
1 2 0 5 3 4 

时间复杂度： O(n)
辅助空间： O(1)