SGU 199 Beautiful People

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
#define N 500010
int pre[N],id[N];
struct peo
{
	int s,b,id;
	void read()
	{
		scanf("%d%d",&s,&b);
	}
	bool operator <(const peo &t)const
	{
		if(s==t.s) return b>t.b;
		else return s<t.s;
	}
}mem[N];
int main()
{
	int n,m,i,j,k;
	while(scanf("%d",&n)!=EOF)
	{
		for(i=1;i<=n;i++)
		{
			mem[i].read();
			mem[i].id=i;
		}
		sort(mem+1,mem+1+n);
		int len=1,low,high;
		id[1]=1;
		for(i=2;i<=n;i++)
		{
			if(mem[id[len]].b<mem[i].b)
			{
				len++;
				id[len]=i;
				pre[i]=id[len-1];
			}
			low=1,high=len;
			while(low<high)
			{
				int mid=(low+high)/2;
				if(mem[id[mid]].b<mem[i].b) low=mid+1;
				else high=mid;
			}
			id[low]=i;
			pre[i]=id[low-1];
		}
		printf("%d\n",len);
		for(i=id[len];i;i=pre[i])
		{
			printf("%d ",mem[i].id);
		}
		printf("\n");
	}
	return 0;
}