OJ-Problems-Source/HDOJ/2491_autoAC.cpp
2016-08-22 00:16:58 +08:00

47 lines
893 B
C++

#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
const int N=100010;
struct darling
{
int s,t,m,mt;
} a[N];
int n;
bool cmp(darling x,darling y)
{
if(x.m==y.m)
return x.s<y.s;
return x.m<y.m;
}
int main()
{
while(~scanf("%d",&n))
{
if(!n)
break;
for(int i=0; i<n; i++)
{
scanf("%d%d",&a[i].s,&a[i].t);
a[i].mt=(a[i].t-a[i].s)/2+1;
a[i].m=a[i].s+a[i].mt;
}
sort(a,a+n,cmp);
int i=0;
for(int t=0; i<n; i++)
{
if(t>a[i].t-a[i].mt)
break;
if(t>=a[i].s)
t+=a[i].mt;
else
t=a[i].m;
}
if(i==n)
printf("YES\n");
else
printf("NO\n");
}
return 0;
}