Submission #367259

#	Time	Username	Problem	Language	Result	Execution time	Memory
367259		PurpleCrayon	Stations (IOI20_stations)	C++17	0 / 100	984 ms	884 KiB

stations

#include "stations.h"
#include <bits/stdc++.h>
using namespace std;

#define sz(v) int(v.size())

int tt;
vector<int> ans;
vector<vector<int>> adj;

void dfs(int c=0, int p=-1, bool b=0){
    if (!b) ans[c] = tt++;
    for (auto nxt : adj[c]) if (nxt != p) dfs(nxt, c, b^1);
    if (b) ans[c] = tt++;
}
vector<int> label(int n, int k, vector<int> u, vector<int> v) {
    ans.assign(n, -1), adj.assign(n, vector<int>()), tt=0;
    for (int i = 0; i < n-1; i++) 
        adj[u[i]].push_back(v[i]), adj[v[i]].push_back(u[i]);
    dfs();
    return ans;
}

int find_next_station(int s, int t, vector<int> c) {
    bool b=s>c[0];

    if (b){ //i'm postorder
        int p = c[0];
        if (sz(c) == 1 || t < c[1] || t > s) //either going out of my subtree, there is no subtree
            return p; 
        
        int ans=-1;
        for (auto nxt : c) if (nxt != p) {
            if (nxt <= t) ans = nxt;
        }
        return ans;

    } else { //i'm preorder
        int p = c[sz(c)-1];
        if (sz(c) == 1 || t < s || t > c[sz(c)-1]) //either going out of my subtree, there is no subtree
            return p;

        int ans=-1;
        for (auto nxt : c) if (nxt != p) {
            if (nxt >= t){
                ans = nxt;
                break;
            }
        }
        return ans;
    }
}

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