zoj 3905 Cake(状压dp)

题目链接：zoj 3905 Cake

代码

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;
const int maxn = 805;

struct State {
    int a, b;
    State (int a = 0, int b = 0): a(a), b(b) {}
    bool operator < (const State& u) const {
        if (b != u.b) return b > u.b;
        return a < u.a;
    }
}S[maxn];

int N, dp[maxn], tmp[maxn];

int solve () {
    memset(dp, 0, sizeof(dp));
    for (int i = 1; i <= N; i++) {
        memcpy(tmp, dp, sizeof(dp));
        for (int j = 1; j <= (i>>1); j++)
            dp[j] = max(dp[j], tmp[j-1] + S[i].a);
    }
    return dp[N>>1];
}

int main () {
    int cas;
    scanf("%d", &cas);
    while (cas--) {
        scanf("%d", &N);
        for (int i = 1; i <= N; i++)
            scanf("%d%d", &S[i].a, &S[i].b);
        sort(S + 1, S + N + 1);
        printf("%d\n", solve());
    }
    return 0;
}