[3] 단속 카메라

#include <algorithm>
#include <string>
#include <vector>

using namespace std;

int solution(vector<vector<int>> routes)
{
    int answer = 1;
    sort(routes.begin(), routes.end());
    int tmp = routes[0][1];

    for (auto a : routes)
    {
        if (tmp < a[0])
        {
            answer++;
            tmp = a[1];
        }
        if (tmp >= a[1])
            tmp = a[1];
    }
    return answer;
}