zoj 3908 Number Game(STL)

代码

#include <cstdio>
#include <cstring>
#include <set>
#include <vector>
#include <algorithm>

using namespace std;
typedef long long ll;
typedef multiset<int>::iterator iter;

int N, M, K;
multiset<int> G;
vector<int> S;

void init () {
G.clear();
scanf("%d%d%d", &N, &M, &K);

int x;
for (int i = 0; i < N; i++) {
scanf("%d", &x);
if (x == 0) continue;
G.insert(x);
}
}

ll solve () {
S.clear();
while (!G.empty()) {
iter it = G.end(); it--;
int u = *it;
G.erase(it);

it = G.upper_bound(K-u);
if (it == G.begin()) continue;

it--;
int v = *it;
G.erase(it);
S.push_back(u * v);
}

ll ret = 0;
sort(S.begin(), S.end());
int n = S.size();
for (int i = 1; i <= M && i <= n; i++) {
ret += S[n-i];
}

return ret;
}

int main () {
int cas;
scanf("%d", &cas);
while (cas--) {
init();
printf("%lld\n", solve());
}
return 0;
}