题解 | #活动安排#

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


int main() {
    int n;
    cin >> n;
    vector<pair<int, int>> arr(n);
    for(int i = 0; i < n; i ++){
        int a, b;
        cin >> a >> b;
        arr[i] = {a, b};
    }
    sort(arr.begin(), arr.end(),[](pair<int, int> &x, pair<int, int> &y){
        return x.second < y.second;
    }
    );

    int start = -1e9, end = -1e9;
    int res = 0;
    for(pair<int, int> v : arr){
        if(end <= v.first){
            end = v.second;
            res ++;
        }
    }
    cout << res << endl;
    return 0;
}
// 64 位输出请用 printf("%lld")