two-strings.c

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

#define MAX_SIZE 100000

int check_string(char s1[], char s2[]);

int main() {

    int n;
    char *s1, *s2;
    
    scanf("%d", &n);
    
    s1=(char*)malloc(sizeof(char)*MAX_SIZE);
    s2=(char*)malloc(sizeof(char)*MAX_SIZE);
    
    char result[n];
    
    for(int i = 0; i <= n; i++){
        scanf("%s", s1);
        scanf("%s", s2);
        result[i] = check_string(s1, s2);
    }
    
    for(int i = 0; i < n; i++){
        printf("%s\n", result[i] == 0 ? "NO" : "YES");
    }
    
    return 0;
}

int check_string(char s1[], char s2[])
{
    int i, j;
    int letters[MAX_SIZE] = {0};
    
    for(i = 0; s1[i] != '\0'; i++){
        letters[s1[i]] += 1;
    }
    
    for(j = 0; s2[j] != '\0'; j++){
        if(letters[s2[j]] > 0){
            return 1;
        }
    }

    
    return 0;
}