Submission #673709

#	Time	Username	Problem	Language	Result	Execution time	Memory
673709		vjudge1	Stations (IOI20_stations)	C++17	0 / 100	868 ms	540 KiB

stations

#include <vector>
//#include "IOI20_Stations.h"
const int N = 1000;
int cnt=0;

std::vector<int> labels;

/*
clarifications:
k == n-1
c is sorted


Debugging:
- Idea => Proof
- Code => Accepted

*/

std::vector<std::vector<int>> g;
void dfs(int node, int par) {
	labels[node] = cnt++;
	for (int ch : g[node]) {
		if (ch != par) {
			dfs(ch, node);
		}
	}
	labels[node] += N * (cnt++);
}

std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v) {
	/*
	1. Construct adjacency list
	2. Label every node with its mrg(dt,ft)
	*/
	g.clear();
	g.resize(n);
	for (int i = 0; i < n - 1;i++) {
		g[u[i]].push_back(v[i]);
		g[v[i]].push_back(u[i]);
	}
	cnt = 0;
	labels.clear();
	labels.resize(n);
	dfs(0, -1);
	return labels;
}

/*
1. Now it's easy to find where to countinue the path
2. Tha path will be behined (i.e. the parent of current node), if the distinatin was greater than it
3. The path will be greater than or equal to any of the nighbours
4. If the distination was greater than or equals the node i, and less than any nighbour greater than i, then we need to go there
*/
int find_next_station(int s, int t, std::vector<int> c) {
	int sz = c.size();
	
	for (int i = 0; i < sz-1; i++) {
		// The destination is under this child, Because it's impossible that it was discovered after that, or before that
		if (t%N >= c[i]%N && t/N <= c[i+2]/N)
			return c[i];
	}
	return c[sz - 1];
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 8
• Subtask 3: 0 / 16
• Subtask 4: 0 / 10
• Subtask 5: 0 / 61