Submission #1269018

#	Time	Username	Problem	Language	Result	Execution time	Memory
1269018		coderg	꿈 (IOI13_dreaming)	C++20	100 / 100	56 ms	17096 KiB

dreaming

/* 11.09.2025 */
#include <bits/stdc++.h>
#include "dreaming.h"
using namespace std;
typedef long long ll;
#define F first
#define S second

vector<vector<pair<int,int>>> adj;
vector<pair<int,int>> dp1,dp2,path;
vector<int> pt,used;

void dfs1(int v,int e){
    used[v]=1;
    pt.push_back(v);
    for(auto &u:adj[v]){
        if(u.F==e)continue;
        dfs1(u.F,v);
        int val=dp1[u.F].F+u.S;
        if(val>=dp1[v].F){
            dp2[v]=dp1[v];
            dp1[v]={val,u.F};
        }else if(val>=dp2[v].F){
            dp2[v]={val,u.F};
        }
    }
}

void dfs2(int v,int e){
    for(auto &u:adj[v]){
        if(u.F==e)continue;
        int val;
        if(u.F==dp1[v].S)val=dp2[v].F+u.S;
        else val=dp1[v].F+u.S;
        if(val>=dp1[u.F].F){
            dp2[u.F]=dp1[u.F];
            dp1[u.F]={val,v};
        }else if(val>=dp2[u.F].F){
            dp2[u.F]={val,v};
        }
        dfs2(u.F,v);
    }
}

void init(int pos){
    pt.clear();
    dfs1(pos,-1);
    dfs2(pos,-1);
    int mx=0;
    for(auto v:pt){
        mx=max(mx,dp1[v].F+dp2[v].F);
    }
    int idx=-1;
    int mn=INT_MAX;
    for(auto v:pt){
        int val=dp1[v].F+dp2[v].F;
        if(val==mx){
            int x=max(dp1[v].F,dp2[v].F);
            if(x<mn){
                mn=x;
                idx=v;
            }
        }
    }
    path.push_back({mn,idx});
}

int travelTime(int N,int M,int L,int a[],int b[],int t[]){
    adj.assign(N,vector<pair<int,int>>());
    dp1.assign(N,{0,-1});
    dp2.assign(N,{0,-1});
    used.assign(N,0);
    path.clear();
    for(int i=0;i<M;i++){
        int x=a[i],y=b[i];
        ll z=t[i];
        adj[x].push_back({y,z});
        adj[y].push_back({x,z});
    }
    for(int i=0;i<N;i++){
        if(!used[i])init(i);
    }
    sort(path.begin(),path.end(),greater<pair<int,int>>());
    for(int i=1;i<path.size();i++){
        int x=path[i].S,y=path[0].S;
        adj[x].push_back({y,(ll)L});
        adj[y].push_back({x,(ll)L});
    }
    for(int i=0;i<N;i++){
        dp1[i]=dp2[i]={0,-1};
    }
    pt.clear();
    dfs1(0,-1);
    dfs2(0,-1);
    int mx=0;
    for(int i=0;i<N;i++) mx=max(mx,dp1[i].F);

    return mx;
}

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