*[hackerrank]Algorithmic Crush

https://www.hackerrank.com/contests/w4/challenges/crush

第一眼觉得要用线段树，但据说会超时。其实这个可以通过生成pair排序来做。

#include <vector>
#include <cstdlib>
#include <algorithm>
#include <iostream>

using namespace std;

int main() {
	int N, M;
	cin >> N >> M;
	vector<pair<int, int>> vec;
	for (int i = 0; i < M ;i++) {
		int a, b, k;
		cin >> a >> b >> k;
		vec.push_back(make_pair(a, k));
		vec.push_back(make_pair(b + 1, -k));
	}
    sort(vec.begin(), vec.end());
    long long max_val = 0;
    long long cur_val = 0;
    for (int i = 0; i < M * 2; i++) {
        cur_val += vec[i].second;
        max_val = max(max_val, cur_val);
    }
	cout << max_val << endl;
    return 0;
}