pku1925 Spiderman DP

........

Problem: 1925		User: BPM136
Memory: 4560K		Time: 500MS
Language: G++		Result: Accepted

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#define LL long long
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fd(i,a,b) for(int i=a;i>=b;i--)
using namespace std;
inline LL read()
{
	LL d=0,f=1;char s=getchar();
	while(s<'0'||s>'9'){if(s=='-')f=-1;s=getchar();}
	while(s>='0'&&s<='9'){d=d*10+s-'0';s=getchar();}
	return d*f;
}

#define N 1000005
#define DB double
#define M 5005
int f[N];
int p[M],h[M],k[M];
int n,m;

void init()
{
	n=read();
	fo(i,0,n-1)
	{
		p[i]=read(),h[i]=read();
		k[i]=h[i]*h[i]-(h[i]-h[0])*(h[i]-h[0]);
//		cout<<"K:"<<k[i]<<endl;
	}
	memset(f,-1,sizeof(f));
	f[p[0]]=0;
}

void DP()
{
	fo(i,1,n-1)
	{
//		cout<<"xu:"<<i<<"K:"<<k[i]<<' ';
		fd(j,p[i]-1,p[0])
		if(f[j]!=-1)
		{
//			cout<<"w:"<<j<<' '<<(h[i]-j)*(h[i]-j)<<' ';
			if(k[i]<((p[i]-j)*(p[i]-j)))break;
			
			int aim=min(p[n-1],2*p[i]-j);
			if(f[aim]==-1)f[aim]=f[j]+1;
			else f[aim]=min(f[aim],f[j]+1);
		}
//		cout<<endl;
	}
}

void OUT()
{
//	fo(i,0,10)cout<<f[i]<<' ';cout<<endl;
	printf("%d\n",f[p[n-1]]);
}

int main()
{
	int T=read();
	while(T--)
	{
		init();
		DP();
		OUT();
	}
}