友好城市
1 #include<iostream>
2 #include<cstdio>
3 #include<algorithm>
4 using namespace std;
5 const int N=5005;
6
7 struct sn{
8 int s,n;
9 };
10 sn r[N];
11 int cmp(sn x,sn y){
12 return x.n<y.n;
13 }
14 int f[N];
15 int main(){
16 int n,maxx=0;
17 cin>>n;
18 for(int i=1;i<=n;i++)
19 scanf("%d%d",&r[i].s,&r[i].n);
20 sort(r+1,r+n+1,cmp);
21 for(int i=1;i<=n;i++){
22 f[i]=1;
23 for(int j=i-1;j>0;j--){
24 if(r[j].s<r[i].s&&f[i]<f[j]+1)
25 f[i]=f[j]+1;
26 }
27 maxx=max(maxx,f[i]);
28 }
29 printf("%d",maxx);
30 return 0;
31 }
