题解

有种迷一样的讽刺效果

每个城市有1000头牛，然后你现在知道对于自己政党每个城市的选票，把城市划分成三个州，保证在至少两个州内获胜

找出前2K大的然后random_shuffle，直到前K个加起来和后K个加起来都满足超过半数也就是K × 500

代码

#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

#include <cmath>

#include <ctime>

//#define ivorysi

#define MAXN 305

#define eps 1e-8

#define pb push_back

using namespace std;

typedef long long int64;

typedef unsigned int u32;

typedef double db;

int K;

int a[MAXN],sum,id[MAXN];

bool cmp(int c,int d) {

    return a[c] > a[d];

}

int main() {

#ifdef ivorysi

    freopen("f1.in","r",stdin);

#endif

    srand(20020421);

    scanf("%d",&K);

    for(int i = 1 ; i <= 3 * K ; ++i) {id[i] = i;scanf("%d",&a[i]);}

    sort(id + 1,id + 3 * K + 1,cmp);

    for(int i = 1 ; i <= 2 * K ; ++i) sum += a[id[i]];

    while(1) {

	random_shuffle(id + 1,id + 2 * K + 1);

	int S = 0;

	for(int i = 1 ; i <= K ; ++i) S += a[id[i]];

	if(S > K * 500 && sum - S > K * 500) {

	    for(int i = 1 ; i <= 3 * K ; ++i) {

		printf("%d\n",id[i]);

	    }

	    return 0;

	}

    }

}