bzoj3174: [Tjoi2013]拯救小矮人

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
using namespace std;

struct node
{
    int x,y;
}a[2100];
bool cmp(node n1,node n2){return (n1.x+n1.y)<(n2.x+n2.y);}

int f[2100];
int main()
{
    int n;
    scanf("%d",&n);
    memset(f,-1,sizeof(f));f[0]=0;
    for(int i=1;i<=n;i++)
        scanf("%d%d",&a[i].x,&a[i].y),f[0]+=a[i].x;
    sort(a+1,a+1+n,cmp);
    
    int H,tot=0;
    scanf("%d",&H);
    for(int i=1;i<=n;i++)
    {
        for(int j=tot;j>=0;j--)
        {
            if(f[j]+a[i].y>=H)f[j+1]=max(f[j+1],f[j]-a[i].x);
            if(f[tot+1]!=-1)tot++;
        }
    }
    printf("%d\n",tot);
    return 0;
}