Submission #513855

#	Time	Username	Problem	Language	Result	Execution time	Memory
513855		status_coding	Dreaming (IOI13_dreaming)	C++14	100 / 100	74 ms	18660 KiB

dreaming

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

using namespace std;

int ansT;
bool viz[100005];
vector<pair<int, int>> v[100005];

pair<int, int> dfs(int p, int par)
{
    viz[p]=true;

    pair<int, int> ans={0, p};
    for(auto it : v[p])
    {
        if(it.first == par)
            continue;

        pair<int, int> nans = dfs(it.first, p);
        ans = max(ans, {nans.first + it.second, nans.second});
    }

    return ans;
}

bool calcPath(int p, int par, int b, vector<int> &e)
{
    if(p == b)
        return true;

    for(auto it : v[p])
    {
        if(it.first == par)
            continue;

        if(calcPath(it.first, p, b, e))
        {
            e.push_back(it.second);
            return true;
        }
    }

    return false;
}

int solve(int p)
{
    int a = dfs(p, 0).second;
    int b = dfs(a, 0).second;

    vector<int> e;
    calcPath(a, 0, b, e);

    if(e.empty())
        return 0;

    int ans=1e9, sumP=0, sumS=0;

    for(int it : e)
        sumS += it;

    ansT=max(ansT, sumS);

    for(int it : e)
    {
        sumP += it;
        sumS -= it;

        ans=min(ans, max(sumP, sumS));
    }

    return ans;
}

int travelTime(int n, int m, int l, int a[], int b[], int t[])
{
    for(int i=0;i<m;i++)
    {
        v[a[i]+1].push_back({b[i]+1, t[i]});
        v[b[i]+1].push_back({a[i]+1, t[i]});
    }

    int nr=0;
    int ans1=0, ans2=0, ans3=0;

    for(int i=1;i<=n;i++)
    {
        if(!viz[i])
        {
            nr++;

            int nans = solve(i);

            if(nans>ans1)
            {
                ans3=ans2;
                ans2=ans1;
                ans1=nans;
            }
            else if(nans > ans2)
            {
                ans3=ans2;
                ans2=nans;
            }
            else if(nans > ans3)
            {
                ans3=nans;
            }
        }
    }

    if(nr>2)
        return max(ansT, max(l+ans1+ans2, 2*l+ans2+ans3));

    if(nr == 2)
        return max(ansT, l+ans1+ans2);

    return ansT;
}

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