Submission #575606

#	Time	Username	Problem	Language	Result	Execution time	Memory
575606		jack715	Dreaming (IOI13_dreaming)	C++14	14 / 100	39 ms	10796 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define pp pop_back
#define mp make_pair
#define bb back
#define ff first
#define ss second

using namespace std;

int build(int now, int par, vector<int>& dist, vector<vector<pair<int, int> > >& path) {
    dist[now] = 0;
    for (auto next : path[now]) {
        if (next.ff == par) continue; 
        dist[now] = max(dist[now], build(next.ff, now, dist, path)+next.ss);
    }
    return dist[now];
}

pair<int, int> find(int now, int par, int up, vector<int>& dist, vector<vector<pair<int, int> > >& path) {
    vector<pair<int, pair<int, int> > > child;
    for (auto next : path[now]) {
        if (next.ff == par) continue; 
        child.pb({dist[next.ff]+next.ss, next});
    }
    if (child.size() == 0)
        return {up, up};
    sort(child.begin(), child.end());
    for (int i = 0; i < child.size()-1; i++) {
        up = max(up, child[i].ff);
    }
    if (dist[child.back().ss.ff] >= child.back().ss.ss + up)
        return find(child.back().ss.ff, now, up+child.back().ss.ss, dist, path);
    // cout << now << ' ' << up << ' ' << child.back().ff << ' ' << par << '\n';
    return {max(up, child.back().ff), child.back().ff+up};
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    vector<int> dist(N, -1), centre;
    vector<vector<pair<int, int> > > path(N);
    for (int i = 0; i < M; i++) {
        path[A[i]].pb({B[i], T[i]});
        path[B[i]].pb({A[i], T[i]});
    }
    int ans = 0;
    for (int i = 0; i < N; i++) {
        if (dist[i] == -1) {
            build(i, -1, dist, path);
            pair<int, int> ret = find(i, -1, 0, dist, path); 
            centre.pb(ret.ff);
            ans = max(ans, ret.ss);
        }
    }

    sort(centre.begin(), centre.end());
    // for (int a : centre)
    //     cout << a << ' ';
    // cout << '\n';
    int p = centre.back();
    for (int i = 0; i < centre.size()-1; i++) {
        ans = max(ans, p+centre[i]+L);
        p = min(p+L, centre[i]+L);
    }
    return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'std::pair<int, int> find(int, int, int, std::vector<int>&, std::vector<std::vector<std::pair<int, int> > >&)':
dreaming.cpp:31:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |     for (int i = 0; i < child.size()-1; i++) {
      |                     ~~^~~~~~~~~~~~~~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:62:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |     for (int i = 0; i < centre.size()-1; i++) {
      |                     ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 0 / 10
• Subtask 3: 0 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23