poj2392 Space Elevator

思路：

排序+dp。

实现：

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;

const int INF = 0x3f3f3f3f;

int K, dp[405][40005];
struct node
{
    int h, a, n;
};
node a[405];

bool cmp(const node & x, const node & y)
{
    return x.a < y.a;
}

int solve()
{
    for (int j = 0; j <= 40000; j++)
    {
        dp[K][j] = j;
    }
    for (int i = K - 1; i >= 0; i--)
    {
        for (int j = 0; j <= 40000; j++)
        {
            dp[i][j] = -INF;
            for (int t = 0; t <= a[i].n; t++)
            {
                if (j + t * a[i].h > a[i].a)
                    break;
                dp[i][j] = max(dp[i][j], dp[i + 1][j + t * a[i].h]);
            }
        }
    }
    return dp[0][0];
}

int main()
{
    cin >> K;
    for (int i = 0; i < K; i++)
    {
        cin >> a[i].h >> a[i].a >> a[i].n;
    }
    sort(a, a + K, cmp);
    cout << solve() << endl;
    return 0;
}