collecting packages

使用map存下每一列的最大值与最小值
合法条件，后一列最小值大于等于前一列最大值

#include<bits/stdc++.h>

using namespace std;

int main() {
	int n;
	cin >> n;
	while (n--) {
		int m;
		cin >> m;
		map<int, vector<int>>c;
		string s;
		while (m--) {
			int x, y;
			cin >> x >> y;
			if (c.count(x) == 0) {
				c[x].push_back(y);
				c[x].push_back(y);
			}
			else if (c[x][1] < y) {
				c[x][1] = y;

			}
			else if (c[x][0] > y)c[x][0] = y;
		}
		int tr = 0;
		int tc = 0;
		for (int i = 0; i < 1001; i++) {
			if (c.count(i))
			{
				while (i - tr) {
					s += "R";
					tr++;
				}
				if (c[i][0] < tc) {
					cout << "NO" << endl;
					goto w;
				}
				while (c[i][1] - tc)
				{
					s += "U";
					tc++;
				}
			}
		}
		cout << "YES" << endl;
		cout << s << endl;
	w:;
	}
}