WA on 1,2 求hack

#include<bits/stdc++.h>
#define int long long
using namespace std;
inline bool _u(char x){return x>='0'&&x<='9';}
inline int read(){
	int x=0,f=1;
	char ch=getchar();
	for(;!_u(ch);ch=='-'&&(f=-1),ch=getchar());
	for(;_u(ch);x=(x<<1)+(x<<3)+(ch^48),ch=getchar());
	return x*f;
}
inline void write(int num,bool flag=0){
	static int st[39],tp=0;
	num<0&&(putchar('-'),num=-num);
	do st[++tp]=num%10;while(num/=10);
	while(tp) putchar(st[tp--]|48);
	putchar(flag?'\n':' ');
	return;
}
template<typename...Args>
inline void write(int t,Args...args){
	write(t),write(args...);
	return;
}
const int N=2010;
vector<pair<int,int> >a,b;
int n;
int dp[N*2],sum;//获得 i 个挂钩的最大喜悦值。 
signed main(){
//	freopen("hangings.in","r",stdin),freopen("hangings.out","w",stdout); 
	n=read();
	for(int i=1,x,y;i<=n;++i){
		x=read(),y=read();
		if(x) b.emplace_back(y,x),sum+=x;
		else a.emplace_back(x,y);
	}
	sort(a.begin(),a.end(),greater<pair<int,int> >());
	sort(b.begin(),b.end(),greater<pair<int,int> >());
	memset(dp,0xcf,sizeof dp);
	dp[1]=0;
	for(int i=0,x,y;i<(int)b.size();++i){
		tie(y,x)=b[i];
		for(int j=n*2;j>=x-1;--j)
			dp[j]=max(dp[j],dp[j-x+1]+y);
		for(int j=n*2-1;~j;--j) dp[j]=max(dp[j+1],dp[j]);
	}
	int ans=max(ans,dp[0]);
	sum=0;
	for(int i=0;i<a.size();++i){
		sum+=a[i].second;
		ans=max(ans,sum+dp[i+1]);
	}
	write(ans,true);
	return(39-39);
}