bzoj千题计划208：bzoj3174: [Tjoi2013]拯救小矮人

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
 
using namespace std;
 
#define N 2001
 
struct node
{
    int a,b;
}e[N];
 
int f[N];
 
void read(int &x)
{
    x=0; char c=getchar();
    while(!isdigit(c)) c=getchar();
    while(isdigit(c)) { x=x*10+c-‘0‘; c=getchar(); }
}
 
bool cmp(node p,node q)
{
    return p.a+p.b<q.a+q.b;
}
 
int main()
{
    int n;
    read(n);
    int sum=0;
    memset(f,-1,sizeof(f));
    f[0]=0;
    for(int i=1;i<=n;++i) 
    {
        read(e[i].a);read(e[i].b);
        f[0]+=e[i].a;
    }
    int h;
    read(h);
    sort(e+1,e+n+1,cmp);
    int ans=0;
    for(int i=1;i<=n;++i)
    {
        for(int j=ans;j>=0;--j)  
            if(f[j]+e[i].b>=h) f[j+1]=max(f[j+1],f[j]-e[i].a);
        if(f[ans+1]>=0) ans++;
    }
    cout<<ans;
}