题解 | #字符个数统计#

#include <stdio.h>

int main() {
    char a;
    char b[999999];
    int i = 0, j, k = 0;
    while ((a = getchar()) != '\n') {
        b[i] = a;
        for (j = 0; j < i; j++) {
            if (b[j] == a) {
                k++;
                break;
            }
        }
        i++;
    }
    printf("%d", i - k);

    return 0;
}