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poj 3624 Charm Bracelet
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 38561 | Accepted: 16727 |
Description
Bessie has gone to the mall‘s jewelry store and spies a charm bracelet. Of course, she‘d like to fill it with the best charms possible from the N (1 ≤ N ≤ 3,402) available charms. Each charm i in the supplied list has a weight Wi (1 ≤ Wi ≤ 400), a ‘desirability‘ factor Di (1 ≤ Di ≤ 100), and can be used at most once. Bessie can only support a charm bracelet whose weight is no more than M (1 ≤ M ≤ 12,880).
Given that weight limit as a constraint and a list of the charms with their weights and desirability rating, deduce the maximum possible sum of ratings.
Input
* Line 1: Two space-separated integers: N and M
* Lines 2..N+1: Line i+1 describes charm i with two space-separated integers: Wi and Di
Output
* Line 1: A single integer that is the greatest sum of charm desirabilities that can be achieved given the weight constraints
Sample Input
4 6 1 4 2 6 3 12 2 7
Sample Output
23
题目大意:意思就是给定你手上能承受多少珠子,然后要尽可能的选择价值大重量轻的珠子戴在手上,最后输出最大的价值。
题目思路:典型的0-1背包问题,一直WA的原因就是把它弄成了完全背包问题。若用完全背包的贪心策略,只能选出局部看来最优的方案,但是用动态规划可以解决这个问题。
#include<iostream> #include<string.h> using namespace std; int max(int a,int b){ return a>b?a:b; } int main(){ int wi,di; int dp[15000]; int N,M; memset(dp,0,sizeof(dp)); cin>>N>>M; for(int i=1;i<=N;i++){ cin>>wi>>di;//从输入开始判断能否放入这个珠子 for(int j=M;j>0;j--){//同样通过数组记录最大值 if(j>=wi) dp[j]=max(dp[j],dp[j-wi]+di);//放完后的价值和未放之前的价值与放入的价值之和相比较,大的那方更新数组 } } cout<<dp[M]<<endl; }
poj 3624 Charm Bracelet