hdu 3466 Proud Merchants（DP）

Proud Merchants

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/65536 K (Java/Others)

Problem Description

Recently, iSea went to an ancient country. For such a long time, it was the most wealthy and powerful kingdom in the world. As a result, the people in this country are still very proud even if their nation hasn’t been so wealthy any more.
The merchants were the most typical, each of them only sold exactly one item, the price was Pi, but they would refuse to make a trade with you if your money were less than Qi, and iSea evaluated every item a value Vi.
If he had M units of money, what’s the maximum value iSea could get?

 

Input

There are several test cases in the input.

Each test case begin with two integers N, M (1 ≤ N ≤ 500, 1 ≤ M ≤ 5000), indicating the items’ number and the initial money.
Then N lines follow, each line contains three numbers Pi, Qi and Vi (1 ≤ Pi ≤ Qi ≤ 100, 1 ≤ Vi ≤ 1000), their meaning is in the description.

The input terminates by end of file marker.

 

Output

For each test case, output one integer, indicating maximum value iSea could get.

 

Sample Input

2 1010 15 105 10 53 105 10 53 5 62 7 3

题意：有一个人到一座城买东西，他共有M钱，但是商人每次只与他交换一个项目价值为V，需要花费P，且若商人的钱少于Q，则不与交换，求出商人用M钱所能换的的最大价值。

思路：比较特殊的DP，要先按照q-p由小到大排序。因为比如 7,12，10和7,6,10，一定是先交换7,12,10；

#include <iostream>#include <cstring>#include <cstdio>#include<cmath>#include <algorithm>using namespace std; struct point{     int p;     int q;     int v;     bool operator < (const point b)const      {        return q-p<b.q-b.p;           } };int main(){  point s[510];  int n,m,i,j;  int pi,qi,vi,t;  int dp[5050];  while(~scanf("%d%d",&n,&m))  {     memset(dp,0,sizeof(dp));      for(i=0;i<n;i++)      {          scanf("%d%d%d",&s[i].p,&s[i].q,&s[i].v);          }      sort(s,s+n);     for(i=0;i<n;i++)     {         qi=s[i].q;         pi=s[i].p;         vi=s[i].v;     for(t=m;t>=qi;t--)        dp[t]=max(dp[t],dp[t-pi]+vi);     }  cout<<dp[m]<<endl;  }    return 0;}