poj2184 对01背包更深刻的认识

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<string>
#include<vector>
#include<queue>
#include<cmath>
#include<memory.h>

using namespace std;

#define INF 0xfffffff

int dp[200002];

int n;

struct Node
{
int s,f;
}node[102];

void clear()
{
memset(node,0,sizeof(node));
}

int main()
{
int left,right;
while(cin>>n)
{
clear();
left=right=0;
for(int i=1;i<=n;i++)
{
scanf("%d %d",&node[i].s,&node[i].f);
if(node[i].s>0)
right+=node[i].s;
else
left+=node[i].s;
}
for(int i=0;i<=right-left;i++)
dp[i]=-INF;
dp[-left]=0;
for(int i=1;i<=n;i++)
{
if(node[i].s>=0)
for(int j=right-left;j>=node[i].s;j--)
dp[j]=max(dp[j],dp[j-node[i].s]+node[i].f);
else
for(int j=0;j<=right-left+node[i].s;j++)
dp[j]=max(dp[j],dp[j-node[i].s]+node[i].f);
}
int ans=0;
for(int i=-left;i<=right-left;i++)
if(dp[i]>=0 && i+dp[i]>ans)
ans=i+dp[i];
if(ans==0)
puts("0");
else
cout<<ans+left<<endl;
}
}