摘要： 水。#include #include bool f(int n){ int t = (int)sqrt(n); for(int i = 2; i <= t; ++i) if(n % i == 0) return 0; return 1;}int main(){ int a[30] = {0, 3, 7}, i; for(i = 3; i != 30; ++i) a[i] = a[i - 1] + a[i - 2]; while(scanf("%d", &i), i != -1) printf(f(a[i]) == 0 ? "No\n" : 阅读全文

摘要： 直接打表。 #include #define MAX 500000 + 2int a[MAX];void count(){ int t = MAX / 2, i, j; for(i = 1; i != t; ++i) for(j = i * 2; j <= MAX; j += i) a[j] += i;}int main(){ int t, n; count(); scanf("%d", &t); while(t-- && scanf("%d", &n)) printf("%d\n", a[n]) 阅读全文