백준 1931번 C++

#include <iostream>

#include <vector>

#include <algorithm>

using namespace std;

int n;

vector<pair<int, int>> time;

bool cmp(pair<int, int> p1, pair<int, int> p2) {

if (p1.second == p2.second)

return p1.first < p2.first;

return p1.second < p2.second;

}

int calcounts() {

int answer = 1;

int start;

int end = time[0].second;

for (int i = 1; i < time.size(); i++) {

if (time[i].first >= end) {

answer++;

end = time[i].second;

}

}

return answer;

}

int main(void) {

cin >> n;

time.resize(n);

for (int i = 0; i < n; i++) {

int start, end;

cin >> start >> end;

time[i] = make_pair(start, end);

}

sort(time.begin(), time.end(), cmp);

cout << calcounts();

return 0;

}