Submission #305079

#	Time	Username	Problem	Language	Result	Execution time	Memory
305079		MarcoMeijer	Stations (IOI20_stations)	C++14	100 / 100	1160 ms	24832 KiB

stations

#include "stations.h"
#include <bits/stdc++.h>

using namespace std;

#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define RE(a,b) REP(a,0,b)
#define FOR(a,b) for(auto& a:b)
#define pb push_back
#define fi first
#define se second
#define all(a) a.begin(), a.end()

typedef long long ll;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;

const int INF=1e9;
const int MX=5e5;

int  M;
vi adj[MX];
vi lab;

void dfs(int u, int p=-1, bool pre=1) {
    if( pre) lab[u] = M++;
    FOR(v,adj[u]) if(v!=p) dfs(v,u,!pre);
    if(!pre) lab[u] = M++;
}

vi label(int n, int k, vi U, vi V) {
    lab.assign(n,0);
    RE(i,n) adj[i].clear();
    RE(i,n-1) {
        adj[U[i]].pb(V[i]);
        adj[V[i]].pb(U[i]);
    }

    M=0;
    dfs(0);
    return lab;
}

int find_next_station(int s, int t, vi c) {
    if(c.size() == 1) return c[0];
    if(s < c[0]) {
        // s is pre
        if(s == 0) {
            // s is root
            FOR(i,c) if(i >= t) return i;
        } else {
            int par = c.back();
            if(t < s) return par;
            FOR(i,c) if(i != par && i >= t) return i;
            return par;
        }
    } else {
        // s is post
        int par = c[0];
        if(t > s) return par;
        REV(i,0,c.size()) if(c[i] != par && c[i] <= t) return c[i];
        return par;
    }
    return 0;
}

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