题解 | #[NOIP2008]笨小猴#

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

int fun(int num){
    if(num == 0 || num == 1)
        return 0;
    if(num == 2 || num == 3)
        return 1;
        // i*i <= num
    for(int i = 2; i<=(int)sqrt(num); i++){
        if(num % i == 0)
            return 0;
    }
    return 1;
}
int main() {
    char str[100];
    int cnt[26] = {0};
    scanf("%s", str);
    int maxn = 0, minn = 100;

    for(int i = 0; str[i] != '\0'; i++){
        cnt[str[i] - 'a'] ++;
    }

    for(int i = 0; i < 26; i++){
        if(cnt[i] != 0){
            if(cnt[i] > maxn)
                maxn = cnt[i];
            if(cnt[i] < minn)
                minn = cnt[i];
        } 
    }

    int num = maxn - minn;
    if(fun(num))
        printf("Lucky Word\n%d", num);
    else
        printf("No Answer\n0");

    return 0;
}