Submission #1040255

#	Time	Username	Problem	Language	Result	Execution time	Memory
1040255		DeathIsAwe	Dreaming (IOI13_dreaming)	C++14	100 / 100	37 ms	16308 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
vector<vector<pair<int,int>>> graph;
vector<pair<int,int>> dum;
vector<int> radi, parent, stac, sum;
vector<bool> visited;


void recur(int a) {
    for (pair<int,int> i: graph[a]) {
        if (i.first != parent[a]) {
            recur(i.first);
            sum[a] = max(sum[a], sum[i.first] + i.second);
        }
    }
}


int travelTime(int n, int m, int l, int a[], int b[], int t[]) {
    int node, radius, prevsum, next, radiusprev, temp, temp2, diameter = 0, maxdi = 0;
    bool button;
    for (int i=0;i<n;i++) {
        visited.push_back(false);
        sum.push_back(0);
        graph.push_back(dum);
        parent.push_back(0);
    }
    for (int i=0;i<m;i++) {
        graph[a[i]].push_back(make_pair(b[i], t[i]));
        graph[b[i]].push_back(make_pair(a[i], t[i]));
    }



    for (int i=0;i<n;i++) {
        if (visited[i]) {
            continue;
        }
        if (graph[i].size() == 0) {
            visited[i] = true;
            radi.push_back(0);
            continue;
        }
        if (graph[i].size() != 1) {
            continue;
        }
        stac = {i}; parent[i] = -1;
        while (stac.size() > 0) {
            node = stac.back(); stac.pop_back();
            visited[node] = true;
            for (pair<int,int> j: graph[node]) {
                if (j.first != parent[node]) {
                    parent[j.first] = node;
                    stac.push_back(j.first);
                }
            }
        }
        
        
        
        recur(i);
        radius = sum[i]; prevsum = 0; radiusprev = INT_MAX; node = i; diameter = sum[i];
        while (radiusprev > radius) {
            for (pair<int,int> j: graph[node]) {
                if (j.first == parent[node]) {
                    continue;
                }
                if (sum[j.first] + j.second == sum[node]) {
                    next = j.first;
                    temp2 = j.second;
                }
            }
            temp = 0;
            button = false;
            for (pair<int,int> j: graph[next]) {
                if (j.first == parent[next]) {
                    continue;
                }
                if (!button && sum[j.first] + j.second == sum[next]) {
                    button = true;
                    continue;
                }
                temp = max(temp, sum[j.first] + j.second);
            }
            diameter = max(diameter, temp + sum[next]);
            prevsum = max(prevsum + temp2, temp);
            radiusprev = radius; radius = max(prevsum, sum[next]); node = next;
            //cout << radiusprev << ' ' << radius << ' ' << prevsum << '\n';
        }
        //cout << radiusprev << '\n' << '\n';
        radi.push_back(radiusprev);
        maxdi = max(maxdi, diameter);
    }
    //for (int i: radi) {
    //    cout << i << ' ';
    //}
    //cout << '\n';

    sort(radi.begin(), radi.end(), greater<int>());
    if (radi.size() == 1) {
        return maxdi;
    } else if (radi.size() == 2) {
        return max(radi[0] + radi[1] + l, maxdi);
    }
    return max(max(radi[0] + radi[1], radi[1] + radi[2] + l) + l, maxdi);
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:87:35: warning: 'temp2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   87 |             prevsum = max(prevsum + temp2, temp);
      |                           ~~~~~~~~^~~~~~~
dreaming.cpp:76:45: warning: 'next' may be used uninitialized in this function [-Wmaybe-uninitialized]
   76 |             for (pair<int,int> j: graph[next]) {
      |                                             ^

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