Submission #867580

#	Time	Username	Problem	Language	Result	Execution time	Memory
867580		dpsaveslives	Dreaming (IOI13_dreaming)	C++17	0 / 100	1022 ms	8012 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
#define f first
#define s second
using namespace std;
int n;
const int MAXN = 1e5+10;
bool visited[MAXN],visited2[MAXN];
vector<pair<int,int>> adj[MAXN];
pair<int,int> dijkstra(bool* vis, int src){
    pair<int,int> ret; ret.f = ret.s = -1;
    priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>> pq;
    pq.push({0,src}); vis[src] = true;
    while(!pq.empty()){
        int u = pq.top().s, d = pq.top().f;
        if(ret.f < d){
            ret.f = d;
            ret.s = u;
        }
        for(auto p : adj[u]){
            if(!vis[p.f]){
                vis[p.f] = true;
                pq.push({d+p.s,p.f});
            }
        }
    }
    return ret;
}

int longpath(int u){
    int a = dijkstra(visited,u).s;
    return dijkstra(visited2,a).f;
}
int res = 0, l;
bool dfs(int curu, int p, int tar, int d){
    for(auto x : adj[curu]){
        if(x.f != p){
            if(dfs(x.f,curu,tar,d+x.s)){
                res = min(res,max(d,l-d));
                return true;
            }
        }
    }
    return false;
}
int calc(int u){
    int a = dijkstra(visited,u).s;
    pair<int,int> val = dijkstra(visited2,u);
    int b = val.s;
    res = val.s; l = val.s;
    dfs(a,-1,b,0);
    return res;
}
int travelTime(int N,int M,int L,int A[],int B[],int T[]){
    n = N;
    for(int i = 0;i<M;++i){
        int u = A[i],v = B[i],w = T[i];
        adj[u].push_back({v,w}); adj[v].push_back({u,w});
    }
    int ans = 0;
    for(int i = 0;i<N;++i){
        if(!visited[i]){
            ans = max(ans,longpath(i));
        }
    }
    memset(visited,false,sizeof(visited)); memset(visited2,false,sizeof(visited2));
    vector<int> results;
    for(int i = 0;i<N;++i){
        if(!visited[i]){
            results.push_back(calc(i));
        }
    }
    sort(results.rbegin(),results.rend());
    if(results.size() > 1){
        ans = max(ans,results[0]+results[1]+L);
    }
    if(results.size() > 2){
        ans = max(ans,results[1]+results[2]+2*L);
    }
    return ans;
}

• Subtask 1: 0 / 14
• Subtask 2: 0 / 10
• Subtask 3: 0 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23