[DP]Atcoder CODE FESTIVAL 2017 Final (Parallel) D

只要按照H+P排序一下DP就好了，至于为什么按H+P排序自己分类讨论一下就懂了。

代码:

#include<cstdio>#include<cstring>#include<algorithm>using namespace std;#define N 5005#define ll long longinline char tc(void){    static char fl[10000],*A=fl,*B=fl;    return A==B&&(B=(A=fl)+fread(fl,1,10000,stdin),A==B)?EOF:*A++;}inline int read(void){    int a=0;char c;    while((c=tc())<'0'||c>'9');    while(c>='0'&&c<='9')a=a*10+c-'0',c=tc();    return a;}struct Zab{    int h,p,s;    inline bool operator<(const Zab&a)const{return s<a.s;}}a[N];int n,ans;ll f[N][N];int main(void){    register int i,j;    n=read();    for(i=1;i<=n;++i)        a[i].h=read(),a[i].p=read(),a[i].s=a[i].h+a[i].p;    sort(a+1,a+n+1);    for(i=1;i<=n;++i)        for(j=n;j;--j){            if((f[i-1][j-1]^(j==1))&&f[i-1][j-1]<=a[i].h)                f[i][j]=(f[i][j]==0?f[i-1][j-1]+a[i].p:min(f[i][j],f[i-1][j-1]+a[i].p)),ans=max(ans,(bool)f[i][j]*j);            if(f[i-1][j])f[i][j]=min(f[i][j],f[i-1][j]);            if(!f[i][j])f[i][j]=f[i-1][j];        }    printf("%d",ans);    return 0;}