uva 11246 - K-Multiple Free set(数论)

题目链接：uva 11246 - K-Multiple Free set

题目大意：给定n，k。求一个元素不大于n的子集，要求该子集的元素尽量多，并且不含两个数满足a∗k=b.

解题思路：容斥原理，f(i)=(−1)inki,取f函数的和即可。

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;typedef long long ll;ll solve (ll n, ll k) {    ll ans = 0, sign = 1;    while (n) {        ans += sign * n;        n /= k;        sign *= -1;    }    return ans;}int main () {    int cas;    scanf("%d", &cas);    while (cas--) {        ll n, k;        scanf("%lld%lld", &n, &k);        printf("%lld\n", solve(n, k));    }    return 0;}