P2782 友好城市

Posted 2022-04-18 ukcxrtjr

题面:https://www.luogu.org/problemnew/show/P2782

本题可以以南岸或是北岸为关键字先从小到大排序,再在另一岸找最长上升子序列即可。

Code:
#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<ctime>
using namespace std;
const int N=200005;
int m,b[N],len,d[N];
struct Node
    int n,s;
a[N];
bool cmp(Node p,Node q)
    if(p.n==q.n)
        return p.s<q.s;
    
    return p.n<q.n;

int main()
    scanf("%d",&m);
    for(int i=1;i<=m;i++)
        scanf("%d%d",&a[i].n,&a[i].s);
    
    sort(a+1,a+1+m,cmp);
    d[++len]=a[1].s;
    for(int i=2;i<=m;i++)
        if(a[i].s>d[len])
            d[++len]=a[i].s;
        
        else
            int j=upper_bound(d+1,d+1+len,a[i].s)-d;
            d[j]=a[i].s;
        
    
    printf("%d\n",len);
    return 0;