给定整数元素的数组arr [] ，任务是将它们排列成使这些数字形成尽可能小的数字的方式。
例如，如果给定的数组为{5，6，2，9，21，1}，则排列将为1212569。
例子：
Input: arr[] = {5, 6, 2, 9, 21, 1}
Output: 1212569
Input: arr[] = {1, 2, 1, 12, 33, 211, 50}
Output: 111221123350
方法：如果所有给定的数字最多为一位，那么简单的方法是将所有数字按升序排序。但是，如果总和数超过一位，则此方法将不起作用。
因此，我们必须通过以下方式比较任何两个元素来对数组进行排序：
如果元素是A和B ，则将(A + B)与(B + A)进行比较，其中+表示串联。
下面是上述方法的实现：
C++
// C++ implementation of the approach
#include
#include
using namespace std;
// Utility function to print
// the contents of an array
void printArr(int arr[], int n)
{
for (int i = 0; i < n; i++)
cout << arr[i];
}
// A comparison function that return true
// if 'AB' is smaller than 'BA' when
// we concatenate two numbers 'A' and 'B'
// For example, it will return true if
// we pass 12 and 24 as arguments.
// This function will be used by sort() function
bool compare(int num1, int num2)
{
// to_string function is predefined function
// to convert a number in string
// Convert first number to string format
string A = to_string(num1);
// Convert second number to string format
string B = to_string(num2);
// Check if 'AB' is smaller or 'BA'
// and return bool value since
// comparison operator '<=' returns
// true or false
return (A + B) <= (B + A);
}
// Function to print the arrangement
// with the smallest value
void printSmallest(int N, int arr[])
{
// If we pass the name of the comparison
// function it will sort the array
// according to the compare function
sort(arr, arr + N, compare);
// Print the sorted array
printArr(arr, N);
}
// Driver code
int main()
{
int arr[] = { 5, 6, 2, 9, 21, 1 };
int N = sizeof(arr) / sizeof(arr[0]);
printSmallest(N, arr);
return 0;
} Java
// Java implementation of the approach
class GFG
{
// Utility function to print
// the contents of an array
public static void printArr(int[] arr, int n)
{
for (int i = 0; i < n; i++)
System.out.print(arr[i]);
}
// A comparison function that return negative
// if 'AB' is smaller than 'BA' when
// we concatenate two numbers 'A' and 'B'
// For example, it will return negative value if
// we pass 12 and 24 as arguments.
// This function will be used during sort
public static int compare(int num1, int num2)
{
// toString function is predefined function
// to convert a number in string
// Convert first number to string format
String A = Integer.toString(num1);
// Convert second number to string format
String B = Integer.toString(num2);
// Check if 'AB' is smaller or 'BA'
// and return integer value
return (A+B).compareTo(B+A);
}
// Function to print the arrangement
// with the smallest value
public static void printSmallest(int N, int[] arr)
{
// Sort using compare function which
// is defined above
for (int i = 0; i < N; i++)
{
for (int j = i + 1; j < N; j++)
{
if (compare(arr[i], arr[j]) > 0)
{
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
}
// Print the sorted array
printArr(arr, N);
}
// Driver code
public static void main(String[] args)
{
int[] arr = { 5, 6, 2, 9, 21, 1 };
int N = arr.length;
printSmallest(N, arr);
}
}
// This code is contributed by
// sanjeev2552Python3
# Python3 implementation of the approach
# Utility function to print
# the contents of an array
def printArr(arr, n):
for i in range(0, n):
print(arr[i], end = "")
# A comparison function that return true
# if 'AB' is smaller than 'BA' when
# we concatenate two numbers 'A' and 'B'
# For example, it will return true if
# we pass 12 and 24 as arguments.
# This function will be used by sort() function
def compare(num1, num2):
# Convert first number to string format
A = str(num1)
# Convert second number to string format
B = str(num2)
# Check if 'AB' is smaller or 'BA'
# and return bool value since
# comparison operator '<=' returns
# true or false
return int(A + B) <= int(B + A)
def sort(arr):
for i in range(len(arr)):
for j in range(i + 1, len(arr)):
if compare(arr[i], arr[j]) == False:
arr[i], arr[j] = arr[j], arr[i]
# Function to print the arrangement
# with the smallest value
def printSmallest(N, arr):
# If we pass the name of the comparison
# function it will sort the array
# according to the compare function
sort(arr)
# Print the sorted array
printArr(arr, N)
# Driver code
if __name__ == "__main__":
arr = [5, 6, 2, 9, 21, 1]
N = len(arr)
printSmallest(N, arr)
# This code is contributed by Rituraj JainC#
// C# implementation for above approach
using System;
class GFG
{
// Utility function to print
// the contents of an array
public static void printArr(int[] arr, int n)
{
for (int i = 0; i < n; i++)
Console.Write(arr[i]);
}
// A comparison function that return negative
// if 'AB' is smaller than 'BA' when
// we concatenate two numbers 'A' and 'B'
// For example, it will return negative value if
// we pass 12 and 24 as arguments.
// This function will be used during sort
public static int compare(int num1, int num2)
{
// toString function is predefined function
// to convert a number in string
// Convert first number to string format
String A = num1.ToString();
// Convert second number to string format
String B = num2.ToString();
// Check if 'AB' is smaller or 'BA'
// and return integer value
return (A+B).CompareTo(B+A);
}
// Function to print the arrangement
// with the smallest value
public static void printSmallest(int N, int[] arr)
{
// Sort using compare function which
// is defined above
for (int i = 0; i < N; i++)
{
for (int j = i + 1; j < N; j++)
{
if (compare(arr[i], arr[j]) > 0)
{
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
}
// Print the sorted array
printArr(arr, N);
}
// Driver code
public static void Main(String[] args)
{
int[] arr = { 5, 6, 2, 9, 21, 1 };
int N = arr.Length;
printSmallest(N, arr);
}
}
// This code is contributed by Rajput-JiPHP
输出：
1212569