Submission #240557

#	Time	Username	Problem	Language	Result	Execution time	Memory
240557		s_avila_g	Dreaming (IOI13_dreaming)	C++17	0 / 100	1084 ms	11768 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"
#define ff first
#define ss second
using namespace std;
int inf = INT_MAX;
vector<vector<pair<int,int> > > gp;
vector<int> vis, dis,parents;

void dfs(int u, int pes){
    vis[u] = 1;
    dis[u] += pes;
    for(auto it: gp[u]){
        if(vis[it.ff] == 0){
            vis[it.ff] = 1;
            parents[it.ff] = u;
            dfs(it.ff, it.ss + dis[u]);
        }
    }
}

int radius(int u){
    int distan1 = dis[u], distan2 = 0, ans = dis[u];
    while(parents[u] != -1){
        ans = min(ans,max(distan1,distan2));
        int pospar = -1;
        for(int i = 0; i < gp[u].size(); i++){
            if(gp[u][i].ff == parents[u]) pospar = gp[u][i].ss;
        }
        u = parents[u];
        distan1 -= pospar; distan2 += pospar;
    }
    return ans;
}

int fndext(int n){
    int ans = -1, maypes = -1;
    for(int i = 0; i < n; i++){
        if(dis[i] > maypes){
            maypes = dis[i];
            ans = i;
        }
    }
    return ans;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    gp.resize(N); vis.resize(N); dis.resize(N); parents.resize(N);
    for(int i = 0; i < N; i++) vis[i] = 0, dis[i] = 0;
    for(int i = 0; i < M; i++){
        gp[A[i]].push_back(make_pair(B[i],T[i]));
        gp[B[i]].push_back(make_pair(A[i],T[i]));
    }
    dfs(0,0);
    int nodext1, nodext2, nodext11, nodext22;
    nodext1 = fndext(N);
    dis.clear();
    for(int i = 0; i < N; i++) vis[i] = 0, dis[i] = 0;
    parents[nodext1] = -1;
    dfs(nodext1,0);
    nodext2 = fndext(N);
    int diam1 = dis[nodext2], diam2;
    for(int i = 0; i < N; i++) dis[i] = 0;
    for(int i = 0; i < N; i++){
        if(vis[i] == 0){
            dfs(i,0);
            nodext11 = fndext(N);
        }
    }
    dis.clear();
    for(int i = 0; i < N; i++) vis[i] = 0, dis[i] = 0;
    parents[nodext11] = -1;
    dfs(nodext11,0);
    nodext22 = fndext(N);
    diam2 = dis[nodext22];
    return max(diam1,max(diam2,radius(nodext22) + radius(nodext2) + L));
}

Compilation message (stderr)

dreaming.cpp: In function 'int radius(int)':
dreaming.cpp:27:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < gp[u].size(); i++){
                        ~~^~~~~~~~~~~~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:72:21: warning: 'nodext11' may be used uninitialized in this function [-Wmaybe-uninitialized]
     parents[nodext11] = -1;
                     ^

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