2022-3-16

#include<bits/stdc++.h>
using namespace std;
typedef pair<int, int> PII;
vector<PII> a;
vector<int> b;
int ans;
int main()
{
    int n,p;scanf("%d",&n);
    while(n--){int l,r;cin>>l>>r;a.push_back({l,r});}
    sort(a.begin(),a.end());
    for(int i=a.size()-1;i>=0;){
        p = a[i].first;ans++,i--;
        while(a[i].first<=p&&a[i].second>=p)i--;
    }
    printf("%d",ans);
    return 0;
}

2024-11-19

#include<bits/stdc++.h>
using namespace std;
const int N = 100010;
struct info{
    int l,r;
    bool operator< (const info &y) const {
        return l < y.l;
    }
}sec[N];
int n;
int main(){
    cin>>n;
    for(int i = 1;i<=n;i ++)cin>>sec[i].l >> sec[i].r;
    int tmp;
    sort(sec+1,sec+1+n);
    int ans = 0;
    for(int i = n;i>=1;){
        ans ++;
        tmp = sec[i].l;
        while(i && sec[i-1].r >= tmp)--i;
        --i;
    }
    cout<<ans<<endl;
    return 0;
}