HDU 3401 Trade[单调队列+dp]

题意：已知股票每天的买入和卖出价格、买入上限和卖出上限以及最多能持有的股票数，问n天后的最大收益是多少。
[cpp]
#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cmath>

using namespace std;

const int oo = 1 << 30;
const int maxn = 2010;
int tcase;
int t, maxp, w;
int ap[maxn], bp[maxn];
int as[maxn], bs[maxn];
int dp[maxn][maxn];
int head, tail;
int q[maxn][2];

void DP()
{
    for (int i = 0; i < maxn; ++i) {
        for (int j = 0; j < maxn; ++j) {
            dp[i][j] = -oo;
        }
    }
    // 前w+1天只能买入
    for (int i = 1; i <= w + 1; ++i) {
        for (int j = 0; j <= min(maxp, as[i]); ++j) {
            dp[i][j] = -ap[i] * j;
        }
    }
    for (int i = 2; i <= t; ++i) {
        /*for (int j = 0; j <= maxp; ++j) {
            dp[i][j] = max(dp[i][j], dp[i-1][j]);
        }
        if (i <= w + 1) continue;
        */
        head = tail = 0;
        for (int j = 0; j <= maxp; ++j) {
            dp[i][j] = max(dp[i][j], dp[i-1][j]);
            if (i <= w + 1) continue;
            while (head < tail && q[tail-1][1] <= dp[i-w-1][j] + ap[i] * j) {
                tail--;
            }
            q[tail][0] = j;
            q[tail++][1] = dp[i-w-1][j] + ap[i] * j;
            while (head < tail && j - q[head][0] > as[i]) {
                head++;
            }
            dp[i][j] = max(dp[i][j], q[head][1] - ap[i] * j);
        }
        head = tail = 0;
        for (int j = maxp; j >= 0; --j) {
            if (i <= w + 1) continue;
            while (head < tail && q[tail-1][1] <= dp[i-w-1][j] + bp[i] * j) {
                tail--;
            }
            q[tail][0] = j;
            q[tail++][1] = dp[i-w-1][j] + bp[i] * j;
            while (head < tail && q[head][0] - j > bs[i]) {
                head++;
            }
            dp[i][j] = max(dp[i][j], q[head][1] - bp[i] * j);
        }
    }
    int ans = -oo;
    for (int i = 0; i <= maxp; ++i) {
        ans = max(ans, dp[t][i]);
    }
    printf("%d\n", ans);
}

int main()
{
    scanf("%d", &tcase);
    while (tcase--) {
        scanf("%d%d%d", &t, &maxp, &w);
        for (int i = 1; i <= t; ++i) {
            scanf("%d%d%d%d", &ap[i], &bp[i], &as[i], &bs[i]);
        }
        DP();
    }
    return 0;
}

补充：软件开发 , C++ ,