判断一个字符串通过变化字符的位置，是否可以组成回文

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

void findPalind(char *arr)
{
    
    int flag = 0;
    // Find the required answer here. Print Yes or No at the end of this function depending on your inspection of the string
    
    int result[26];
    
    for (int i=0; i<26; i++) {
        result[i] = 0;
    }
    
    int lenth = (int)strlen(arr);
    for (int i=0; i<lenth; i++) {
        int index = (int)*(arr + i) - (int)‘a‘;
        if (result[index] == 0) {
            result[index] = 1;
        } else {
            result[index] = 0;
        }
    }
    
    int sum = 0;
    for (int i=0; i<26; i++) {
        sum += result[i];
    }
    
    if (sum >= 2) {
        flag = 1;
    } else {
        flag = 0;
    }
    
    if (flag==0)
        printf("YES\n");
    else
        printf("NO\n");
    
    return;
}
int main() {
    
    char arr[100001];
    scanf("%s",arr);
    findPalind(arr);
    return 0;
}