题解 | 字符个数统计

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

int main() {
    char str[501];
    int n = 0,m,arr[128] = {0};
    scanf("%s", str);
    int len = strlen(str);
    for (int i = 0; i < len; i++) {
        m = str[i];
        arr[m]++;
        if (arr[m] == 1) {
            n++;
        }
    }
    printf("%d",n);
    return 0;
}