Help me in solving DNASTORAGE problem

help
,
1

My issue

hoe to avoid run-time error

My code

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

int main() {
    int T, N;
    char S[100];  
    scanf("%d", &T);

    while (T--) {
        scanf("%d", &N);
        scanf("%s", S);

        for (int i = 0; i < strlen(S); i += 2) {
            if ((S[i] == '0') && (S[i + 1] == '0'))
                printf("A");
            if ((S[i] == '0') && (S[i + 1] == '1'))
                printf("T");
            if ((S[i] == '1') && (S[i + 1] == '0'))
                printf("C");
            if ((S[i] == '1') && (S[i + 1] == '1'))
                printf("G");
        }printf("\n");
    }

    return 0;
}

Learning course: Strings using C
Problem Link: DNA Storage Practice Problem in - CodeChef

2

@saravanamuruga
make s[1000] instead of 100.