LIS [SWUST OJ 585] 倒金字塔

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define N 100005

struct Rect
{
    int x,y;
    bool operator<(const Rect &t)const
    {
        if(x!=t.x) return x<t.x;
        return y<t.y;
    }
}s[N];

int n;
int len;
int dp[N];

int up_bound(int k)
{
    int l=1,r=len+1;
    while(l<r)
    {
        int m=(l+r)/2;
        if(dp[m]<=k) l=m+1;
        else r=m;
    };
    return l;
}

void solve()
{
    len=1;
    dp[1]=s[1].y;
    for(int i=2;i<=n;i++)
    {
        if(s[i].y>=dp[len]) dp[++len]=s[i].y;
        else
        {
            int pos=up_bound(s[i].y);
            dp[pos]=s[i].y;
        }
    }
}
int main()
{
    while(scanf("%d",&n)!=EOF)
    {
        for(int i=1;i<=n;i++)
        {
            scanf("%d%d",&s[i].x,&s[i].y);
        }
        sort(s+1,s+n+1);
        solve();
        printf("%d\n",len);
    }
    return 0;
}