hdu1171 Big Event in HDU(多重背包)

http://acm.hdu.edu.cn/showproblem.php?pid=1171

多重背包题目不难，但是有些点不能漏或错。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#include<cmath> 
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define IO ios::sync_with_stdio(false);cin.tie(0);
#define INF 1e9
typedef long long ll;
using namespace std;
int n, a[100010], b[100010], dp[500010];
int main()
{
    IO;
    while(cin >> n){
        memset(dp, 0, sizeof(dp)); //不要忘了初始化
        if(n < 0) break;
        int sum = 0;
        for(int i = 0; i < n; i++){
            cin >> a[i] >> b[i];
            sum += a[i]*b[i];
        }
        int half=sum/2;
        for(int i = 0; i < n; i++){
            for(int k = 0; k < b[i]; k++){//多重背包循环是在这里，而不是下面 
                for(int j = half; j >= a[i]; j--){//sum会超时
                    dp[j] = max(dp[j], dp[j-a[i]]+a[i]);
                }
            }
        }
        cout << sum-dp[half] << " " << dp[half] << endl;
    }
    return 0;
}