C++ 代码

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;

typedef pair<int,int> PII;
vector<PII> a;
int res;

int main(){
    int n;
    cin>>n;
    while(n --){
        int l,r;
        cin>>l>>r;
        a.push_back({l,r});
    }

    sort(a.begin(),a.end());

    int end = -2e9;
    for(auto x : a){
        if(x.first > end){
            res ++;
            end = x.second;
        }else{
            end = max(end,x.second);
        }
    }

    cout<<res<<endl;
}