HDU 4133 StrangeStandard 反素数

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反素数：点击打开链接

爆搜幂即可。

#include <iostream>
#include <cstdio>
#include <string.h>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <map>
#include <ctime>
template <class T>
inline bool rd(T &ret) {
	char c; int sgn;
	if (c = getchar(), c == EOF) return 0;
	while (c != '-' && (c<'0' || c>'9')) c = getchar();
	sgn = (c == '-') ? -1 : 1;
	ret = (c == '-') ? 0 : (c - '0');
	while (c = getchar(), c >= '0'&&c <= '9') ret = ret * 10 + (c - '0');
	ret *= sgn;
	return 1;
}
template <class T>
inline void pt(T x) {
	if (x <0) { putchar('-'); x = -x; }
	if (x>9) pt(x / 10);
	putchar(x % 10 + '0');
}
typedef long long ll;
using namespace std;
const ll inf = ((ll)1) << 60;
const int INF = 100000000;
const int N = 100000;
const int mod = 1e7;
ll prime[] {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53};
ll n, ans, siz;
void dfs(ll mul, ll cnt, int pre, int id){
	//mul是当前的数，cnt记录mul的因子个数：因子个数为素数的幂相乘
	if (mul > n)return;
	if (cnt == siz) ans = min(ans, mul);
	if (cnt > siz) ans = mul, siz = cnt;
	for (int i = 1; i <= pre; i++)
	{
		mul *= prime[id];
		if (mul > n)break;
		dfs(mul, cnt * (i+1), i, id + 1);
	}
}
int main(){
	int T, Cas = 1; rd(T);
	while (T--){
		rd(n);
		printf("Case #%d: ", Cas++);
		ans = siz = 0;
		dfs(1, 1, 50, 0);
		pt(ans); puts("");

	}
	return 0;
}