Submission #865995

#	Time	Username	Problem	Language	Result	Execution time	Memory
865995		Onur_Ilgaz	Dreaming (IOI13_dreaming)	C++17	100 / 100	57 ms	16788 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
vector <vector<pair<int, int> > > adj;
vector <int> mxdepth;
bitset <100000> vis;
int mxDia;

void dfs(int node, int ata = -1) {
    vis[node] = 1;
    int arr[3] = {0};
    for(auto &[to, w]:adj[node]) {
        if(to == ata) continue;
        dfs(to, node);
        mxdepth[node] = max(mxdepth[node], mxdepth[to] + w);
        arr[2] = mxdepth[to] + w;
        for(int i = 1; ~i; i--) {
            if(arr[i] < arr[i + 1]) {
                swap(arr[i], arr[i + 1]);
            }
        }
    }
    mxDia = max(arr[0] + arr[1], mxDia);
}

int dfs2(int node, int ust = 0, int ata = -1) {
    // cout<<"node: "<<node<<" "<<ust<<"\n";
    int arr[3] = {0, 0, 0}, brr[3] = {-1, -1, -1};
    for(auto &[to, w]:adj[node]) {
        if(to == ata) continue;
        arr[2] = mxdepth[to] + w;
        brr[2] = to;
        for(int i = 1; ~i; i--) {
            if(arr[i] < arr[i + 1]) {
                swap(arr[i], arr[i + 1]);
                swap(brr[i], brr[i + 1]);
            }   
        }
    }

    for(auto &[to, w]:adj[node]) {
        if(to == ata) continue;
        int othermax = to == brr[0] ? arr[1] : arr[0];
        int ifgoust = max(ust + w, othermax + w);
        int valifto = max(mxdepth[to], ifgoust);
        // cout<<arr[0]<<" "<<arr[1]<<"\n";
        // cout<<brr[0]<<" "<<brr[1]<<"\n";
        // cout<<to<<" "<<othermax<<" "<<ifgoust<<" "<<valifto<<"\n";
        if(max(ust, mxdepth[node]) > valifto) {
            return dfs2(to, ifgoust, node);
        }
    }
    return max(ust, mxdepth[node]);
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    adj.assign(N, vector <pair<int, int> > (0));
    mxdepth.assign(N, 0);
    for(int i = 0; i < M; i++) {
        int a = A[i], b = B[i], t = T[i];
        adj[a].push_back({b, t});
        adj[b].push_back({a, t});
    }
    vector <int> trees;
    for(int i = 0; i < N; i++) {
        if(!vis[i]) {
            dfs(i);
            int depth = dfs2(i);
            trees.push_back(depth);
            // cout<<"\n";
        }
    }
    if(trees.size() == 1) {
        return mxDia;
    }
    sort(trees.begin(), trees.end());
    reverse(trees.begin(), trees.end());
    int ans = max(mxDia, trees[0] + trees[1] + L);
    // cout<<trees[0]<<" "<<trees[1]<<"\n";
    if(trees.size() > 2) {
        ans = max(ans, trees[1] + trees[2] + 2 * L);
    }
    return ans;
}

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