回文串判断

#include <stdio.h>

int main(int argc, const char * argv[]) {
    
    char a[101], s[101];
    int len, mid, next, top;
    
    gets(a);
    len = strlen(a);
    mid = len/2 - 1;
    // abc cba
    top = 0;
    for (int i=0; i<=mid; i++) {
        s[top++] = a[i];
    }
    printf("%s", s);
    
    if (len%2 == 0) {
        next = mid+1;
    }else{
        next = mid +2;
    }
    
    for (int i=next; i<=len-1; i++) {
        if (a[i] != s[--top]) {
            break;
        }
    }
    
    if (top == 0) {
        printf("YES");
    }else {
        printf("NO");
    }
    
    return 0;
}