Submission #843723

#	Time	Username	Problem	Language	Result	Execution time	Memory
843723		nonono	Dreaming (IOI13_dreaming)	C++14	100 / 100	82 ms	36324 KiB

dreaming

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

vector<vector<pair<int, int>>> adj;
vector<int> mark;
vector<int> high, _high;
vector<int> vertex;

void dfs(int u, int par) {
    vertex.push_back(u);
    mark[u] = 1;
    high[u] = 0;
    
    for(auto [v, w] : adj[u]) {
        if(v == par) continue ;
        dfs(v, u);
        high[u] = max(high[u], high[v] + w);
    }
}

void reroot(int u, int par) {
    vector<pair<int, int>> k;
    vector<int> L, R;
    
    for(auto [v, w] : adj[u]) {
        if(v == par) continue ;
        k.push_back({v, w});
    }
   
   for(int i = 0; i < k.size(); i ++) {
       auto [v, w] = k[i];
       L.push_back(max((!L.empty() ? L.back() : 0), high[v] + w));
   }
   
   for(int i = 0; i < k.size(); i ++) {
       auto [v, w] = k[k.size() - 1 - i];
       R.push_back(max((!R.empty() ? R.back() : 0), high[v] + w));
   }
   
   reverse(R.begin(), R.end());
   
   for(int i = 0; i < k.size(); i ++) {
       auto [v, w] = k[i];
       if(v == par) continue ;
       
       _high[v] = _high[u] + w;
       if(i) _high[v] = max(_high[v], L[i - 1] + w);
       if(i + 1 < R.size()) _high[v] = max(_high[v], R[i + 1] + w);
       reroot(v, u);
   }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    adj.resize(N);
    mark.assign(N, 0);
    high.resize(N);
    _high.resize(N);
    
    for(int i = 0; i < M; i ++) {
        adj[A[i]].push_back({B[i], T[i]});
        adj[B[i]].push_back({A[i], T[i]});
    }
    
    vector<int> f;
    int ans = 0;
    
    for(int i = 0; i < N; i ++) {
        if(!mark[i]) {
            dfs(i, i);
            
            _high[i] = 0;
            reroot(i, i);
            
            int timer = max(high[vertex.back()], _high[vertex.back()]);
            for(int x : vertex) {
                ans = max(ans, high[x] + _high[x]);
                timer = min(timer, max(high[x], _high[x]));
            }
            
            f.push_back(timer);
            vertex.clear();
        }
    }
    
    sort(f.begin(), f.end());
    
    if(f.size() > 1) {
        ans = max(ans, f.back() + f[f.size() - 2] + L);
    }
    
    if(f.size() > 2) {
        ans = max(ans, f[f.size() - 2] + f[f.size() - 3] + 2 * L);
    }
    
    return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'void dfs(int, int)':
dreaming.cpp:15:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   15 |     for(auto [v, w] : adj[u]) {
      |              ^
dreaming.cpp: In function 'void reroot(int, int)':
dreaming.cpp:26:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   26 |     for(auto [v, w] : adj[u]) {
      |              ^
dreaming.cpp:31:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |    for(int i = 0; i < k.size(); i ++) {
      |                   ~~^~~~~~~~~~
dreaming.cpp:32:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   32 |        auto [v, w] = k[i];
      |             ^
dreaming.cpp:36:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |    for(int i = 0; i < k.size(); i ++) {
      |                   ~~^~~~~~~~~~
dreaming.cpp:37:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   37 |        auto [v, w] = k[k.size() - 1 - i];
      |             ^
dreaming.cpp:43:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |    for(int i = 0; i < k.size(); i ++) {
      |                   ~~^~~~~~~~~~
dreaming.cpp:44:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   44 |        auto [v, w] = k[i];
      |             ^
dreaming.cpp:49:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |        if(i + 1 < R.size()) _high[v] = max(_high[v], R[i + 1] + w);
      |           ~~~~~~^~~~~~~~~~

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