检查字符串的两半是否具有相同的字符集

仅给定一个小写字符的字符串，任务是检查是否可以从中间拆分一个字符串，这将产生具有相同字符和每个字符频率相同的两半。如果给定字符串的长度是奇数，则忽略中间元素并检查其余元素。

例子：

Input: abbaab
Output: NO
The two halves contain the same characters
but their frequencies do not match so they
are NOT CORRECT

Input : abccab
Output : YES

算法：

1. 声明两个计数器数组，用于保存字符串，每个大小为 26。
2. 现在运行一个循环并获取两个变量 i 和 j，其中 i 从 0 开始，j 从（字符串长度 - 1）开始。
3. 对于字符串中的每个字符，转到计数器数组中的相应索引，并将值增加 1，并增加 i 和减少 j。这样做直到 i 小于 j。
4. 完成第 3 步后，再次运行循环并比较计数器数组的值。如果第一个数组的值不等于第二个数组的值，则返回 false。
5. 如果所有计数都匹配，则返回 true。

下面是上述想法的实现：

C++

// C++ program to check if it is
// possible to split string or not
#include 
using namespace std;
const int MAX_CHAR = 26;

// function to check if we can split
// string or not
bool checkCorrectOrNot(string s)
{
    // Counter array initialized with 0
    int count1[MAX_CHAR] = {0};
    int count2[MAX_CHAR] = {0};

    // Length of the string
    int n = s.length();
    if (n == 1)
        return true;

    // traverse till the middle element
    // is reached
    for (int i=0,j=n-1; i

---

Java

// Java program to check if it two 
// half of string contain same Character
// set or not
public class GFG {

    static final int MAX_CHAR = 26;
     
    // function to check both halves
    // for equality
    static boolean checkCorrectOrNot(String s)
    {
        // Counter array initialized with 0
        int[] count1 = new int[MAX_CHAR];
        int[] count2 = new int[MAX_CHAR];
     
        // Length of the string
        int n = s.length();
        if (n == 1)
            return true;
     
        // traverse till the middle element
        // is reached
        for (int i = 0, j = n - 1; i < j; i++, j--)
        {
            // First half
            count1[s.charAt(i) - 'a']++;
     
            // Second half
            count2[s.charAt(j) - 'a']++;
        }
     
        // Checking if values are different
        // set flag to 1
        for (int i = 0; i < MAX_CHAR; i++)
            if (count1[i] != count2[i])
                return false;
     
        return true;
    }
     
    // Driver program to test above function
    public static void main(String args[])
    {
        // String to be checked
        String s = "abab";
     
        if (checkCorrectOrNot(s))
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}
// This code is contributed by Sumit Ghosh

Python3

# Python3 program to check if it is
# possible to split string or not
MAX_CHAR = 26

# Function to check if we 
# can split string or not
def checkCorrectOrNot(s):
    
    global MAX_CHAR
    
    # Counter array initialized with 0
    count1 = [0] * MAX_CHAR
    count2 = [0] * MAX_CHAR

    # Length of the string
    n = len(s)
    
    if n == 1:
        return true

    # Traverse till the middle 
    # element is reached
    i = 0; j = n - 1
    
    while (i < j):
        
        # First half
        count1[ord(s[i]) - ord('a')] += 1

        # Second half
        count2[ord(s[j]) - ord('a')] += 1

        i += 1; j -= 1

    # Checking if values are 
    # different set flag to 1
    for i in range(MAX_CHAR):
        
        if count1[i] != count2[i]:
            return False
            
    return True


# Driver Code

# String to be checked
s = "ababc"

print("Yes" if checkCorrectOrNot(s) else "No")


# This code is contributed by Ansu Kumari.

C#

// C# program to check if it two half of 
// string contain same Character set or not
using System;

class GFG {

    static int MAX_CHAR = 26;
    
    // function to check both halves for 
    // equality
    static bool checkCorrectOrNot(string s)
    {
        
        // Counter array initialized with 0
        int []count1 = new int[MAX_CHAR];
        int []count2 = new int[MAX_CHAR];
    
        // Length of the string
        int n = s.Length;
        if (n == 1)
            return true;
    
        // traverse till the middle element
        // is reached
        for (int i = 0, j = n - 1; i < j;
                                   i++, j--)
        {
            
            // First half
            count1[s[i] - 'a']++;
    
            // Second half
            count2[s[j] - 'a']++;
        }
    
        // Checking if values are different
        // set flag to 1
        for (int i = 0; i < MAX_CHAR; i++)
            if (count1[i] != count2[i])
                return false;
    
        return true;
    }
    
    // Driver program to test above function
    public static void Main()
    {
        // String to be checked
        string s = "abab";
    
        if (checkCorrectOrNot(s))
            Console.Write("Yes");
        else
            Console.Write("No");
    }
}

// This code is contributed by nitin mittal

Javascript

// Javascript program to check if it two 
// half of string contain same Character
// set or not
    
    let MAX_CHAR = 26;
    
    // function to check both halves
    // for equality
    function checkCorrectOrNot(s)
    {
        // Counter array initialized with 0
        let count1 = new Array(MAX_CHAR);
        let count2 = new Array(MAX_CHAR);
        for(let i=0;i<MAX_CHAR;i++)
        {
            count1[i]=0;
            count2[i]=0;
        }
       
        // Length of the string
        let n = s.length;
        if (n == 1)
            return true;
       
        // traverse till the middle element
        // is reached
        for (let i = 0, j = n - 1; i < j; i++, j--)
        {
            // First half
            count1[s[i] - 'a']++;
       
            // Second half
            count2[s[j] - 'a']++;
        }
       
        // Checking if values are different
        // set flag to 1
        for (let i = 0; i < MAX_CHAR; i++)
            if (count1[i] != count2[i])
                return false;
       
        return true;
    }    
    
    // Driver program to test above function
    
    // String to be checked
    let  s = "abab";
    if (checkCorrectOrNot(s))
        document.write("Yes");
    else
        document.write("No");
    
    //This code is contributed by avanitrachhadiya2155
    

---

输出 ：

YES

空间优化解决方案：
下面是上述方法的空间优化解决方案。

1. 我们可以通过只使用 1 个计数器数组来解决这个问题。
2. 取一个字符串并增加前半部分的计数，然后减少后半部分的计数。
3. 如果最终计数器数组为 0，则返回 true，否则返回 False。

下面是上述想法的实现：

C++

// C++ program to check if it is
// possible to split string or not
#include 
using namespace std;
const int MAX_CHAR = 26;

// function to check if we can split
// string or not
bool checkCorrectOrNot(string s)
{
    // Counter array initialized with 0
    int count[MAX_CHAR] = {0};

    // Length of the string
    int n = s.length();
    if (n == 1)
        return true;

    // traverse till the middle element
    // is reached
    for (int i=0,j=n-1; i

Java

// Java program to check if it two 
// half of string contain same Character
// set or not
public class GFG {

    static final int MAX_CHAR = 26;
     
    // function to check both halves
    // for equality
    static boolean checkCorrectOrNot(String s)
    {
        // Counter array initialized with 0
        int[] count = new int[MAX_CHAR];
     
        // Length of the string
        int n = s.length();
        if (n == 1)
            return true;
     
        // traverse till the middle element
        // is reached
        for (int i = 0,j = n - 1; i < j; i++, j--)
        {
            // First half
            count[s.charAt(i) - 'a']++;
     
            // Second half
            count[s.charAt(j) - 'a']--;
        }
     
        // Checking if values are different
        // set flag to 1
        for (int i = 0; i < MAX_CHAR; i++)
            if (count[i] != 0)
                return false;
     
        return true;
    }
     
    // Driver program to test above function
    public static void main(String args[])
    {
        // String to be checked
        String s = "abab";
     
        if (checkCorrectOrNot(s))
            System.out.println("Yes");
        else
           System.out.println("No");
    }
}
// This code is contributed by Sumit Ghosh

Python3

# Python3 program to check if it is
# possible to split string or not
MAX_CHAR = 26

# Function to check if we  
# can split string or not
def checkCorrectOrNot(s):
    
    global MAX_CHAR
    
    # Counter array initialized with 0
    count = [0] * MAX_CHAR

    # Length of the string
    n = len(s)
    
    if n == 1:
        return true

    # Traverse till the middle 
    # element is reached
    i = 0; j = n-1
    
    while i < j:
        
        # First half
        count[ord(s[i]) - ord('a')] += 1

        # Second half
        count[ord(s[j])-ord('a')] -= 1

        i += 1; j -= 1

    # Checking if values are 
    # different, set flag to 1
    for i in range(MAX_CHAR):
        
        if count[i] != 0:
            return False

    return True


# Driver Code

# String to be checked
s = "abab"

print("Yes" if checkCorrectOrNot(s) else "No")


# This code is contributed by Ansu Kumari.

C＃

// C# program to check if it two 
// half of string contain same Character
// set or not
using System;

public class GFG {

    static int MAX_CHAR = 26;
    
    // function to check both halves
    // for equality
    static bool checkCorrectOrNot(String s)
    {
        
        // Counter array initialized with 0
        int[] count = new int[MAX_CHAR];
    
        // Length of the string
        int n = s.Length;
        if (n == 1)
            return true;
    
        // traverse till the middle element
        // is reached
        for (int i = 0, j = n - 1; i < j; i++, j--)
        {
            // First half
            count[s[i] - 'a']++;
    
            // Second half
            count[s[j] - 'a']--;
        }
    
        // Checking if values are different
        // set flag to 1
        for (int i = 0; i < MAX_CHAR; i++)
            if (count[i] != 0)
                return false;
    
        return true;
    }
    
    // Driver program to test above function
    public static void Main(String []args)
    {
        
        // String to be checked
        String s = "abab";
    
        if (checkCorrectOrNot(s))
            Console.Write("Yes");
        else
            Console.Write("No");
    }
}

// This code is contributed by parashar.

Javascript

// Javascript program to check if it two
// half of string contain same Character
// set or not
    
let MAX_CHAR = 26;

// Function to check both halves
// for equality
function checkCorrectOrNot(s)
{
    
    // Counter array initialized with 0
    let count = new Array(MAX_CHAR);
    for(let i = 0; i < count.length; i++)
    {
        count[i] = 0;
    }
  
    // Length of the string
    let n = s.length;
    if (n == 1)
        return true;
  
    // Traverse till the middle element
    // is reached
    for(let i = 0, j = n - 1; i < j; i++, j--)
    {
        
        // First half
        count[s[i] - 'a']++;
  
        // Second half
        count[s[j] - 'a']--;
    }
  
    // Checking if values are different
    // set flag to 1
    for(let i = 0; i < MAX_CHAR; i++)
        if (count[i] != 0)
            return false;
  
    return true;
}

// Driver Code
let s = "abab";

if (checkCorrectOrNot(s))
    document.write("Yes");
else
    document.write("No");

// This code is contributed by rag2127
    

输出：

YES