个人思路：

一开始是想把每个时间点的取钥匙和还钥匙保存下来，然后遍历每一个时间点，结果发现时间复杂度太高了，浪费，然后我们可以用堆，就是优先队列，遍历每一个有用的时间的，要实现一下小于号的重载。

AC代码：

#include <bits/stdc++.h>
using namespace std;
struct node {
	int k;
	int op;//0还   1取
	int time;
	bool operator < (const node& n) const {
		if (time != n.time)return time > n.time;
		else if (op != n.op)return op > n.op;
		else if (k != n.k)return k > n.k;
	}
};
priority_queue<node> q;
int keys[1010];
int main() {
	int n, k, w, s, c;
	cin >> n >> k;
	node x;
	while (k--) {
		cin >> w >> s >> c;
		x.k = w;
		x.op = 1;
		x.time = s;
		q.push(x);
		x.op = 0;
		x.time = s + c;
		q.push(x);
	}
	for (int i = 1; i <= n; i++) keys[i] = i;
	while (!q.empty()) {
		x = q.top();
		q.pop();
		if (x.op == 0) {
			for (int i = 1; i <= n; i++) {
				if (keys[i] == -1) {
					keys[i] = x.k;
					break;
				}
			}
		}
		else {
			for (int i = 1; i <= n; i++) {
				if (keys[i] == x.k) {
					keys[i] = -1;
					break;
				}
			}
		}
	}
	int i = 1;
	for (; i < n; i++)
		cout << keys[i] << " ";
	cout << keys[i];
	return 0;
}