“()” “[]”问题

#include <cstdio>
#include <cstring>

char s[60];
int len;

bool kh(int start, int end){
     if(start > len || end > len){
        return true;
     }
     if(start > end){
        return true;
     }
     if(start + 1 == end && (s[start] == ‘(‘ && s[end] == ‘)‘) || (s[start] == ‘[‘ && s[start] == ‘]‘)){
        return true;
     }
     for(int i = start + 1; i <= end; ++i){
        if((s[start] == ‘(‘ && s[i] == ‘)‘) || (s[start] == ‘[‘ && s[i] == ‘]‘)){
           if(kh(start + 1, i - 1) && kh(i + 1, end)){
              return true;
           }
        }
     }
     return false;
}

int main(){
    int n;
    scanf("%d", &n);
    for(int k = 1; k <= n; ++k){
       scanf("%s", s);
       len = strlen(s) - 1;
       if(kh(0, len)){
          printf("Yes\n");
       }else{
          printf("No\n");
       }
       memset(s, 0, sizeof(s));
    }
    return 0;
}