poj 3624 Charm Bracelet(01背包)

Charm Bracelet
Time Limit: 1000MS   Memory Limit: 65536K
Total Submissions: 29295   Accepted: 13143

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

Source

 
一道最简单的01背包,特别简单,而且好理解。
 
题意:第一行第一个数为有几颗珠子,第二个数字表示为最大珠子和的重量,后面每一行表示一个珠子,第一个数为重量,第二数为价值,在最大重量的限制下,求最大限制。
 
附上代码:
 
 #include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int max(int a,int b)
{
return a>b?a:b;
}
int main()
{
int n,m,i,j;
int a[],b[];
while(~scanf("%d%d",&n,&m))
{
for(i=; i<n; i++)
scanf("%d%d",&a[i],&b[i]);
int dp[]; //dp数组的大小wa了一次,要注意必须和最大重量相同,而不是最大珠子个数
memset(dp,,sizeof(dp));
for(i=; i<n; i++)
for(j=m; j>=a[i]; j--)
dp[j]=max(dp[j],dp[j-a[i]]+b[i]); //比较加上这颗珠子和不加的价值谁更大,记录大的那个
printf("%d\n",dp[m]);
}
return ;
}
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