aoc-2020/2.c

#include <stdio.h>

int main() {
    int count = 0;

    int min, max;
    char target;
    char str[100];
    while (scanf("%d-%d %c: %s", &min, &max, &target, str) == 4) {
        int char_count = 0;
        char *str_ptr = str;
        char test_c;
        while ((test_c = *(str_ptr++)) != '\0') {
            if (test_c == target)
                char_count++;
        }
        if (min <= char_count && char_count <= max){
            count++;
        }
    }
    printf("%d\n", count);

    return 0;
}