Submission #251456

#	Time	Username	Problem	Language	Result	Execution time	Memory
251456		hhh07	Dreaming (IOI13_dreaming)	C++14	100 / 100	128 ms	14072 KiB

dreaming

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <utility>
#include <set>
#include <cmath>
#include <climits>
#include <cstring>
#include <stdio.h>
#include <assert.h>
#include "dreaming.h"
 
using namespace std;
 
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> ii;

int N = 1e5 + 1;
vector<vector<ii>> adjList(N, vector<ii> ());
vi visited(N, false);
int dist[100001];
int maxNode, d;
vi r;
void dfs(int curr, int prev, int time){
    visited[curr] = true;
    dist[curr] = time;
    if (time > d){
        maxNode = curr;
        d = time;
    }
    for (int i = 0; i < adjList[curr].size(); i++){
        int idx = adjList[curr][i].first, t = adjList[curr][i].second;
        if (idx != prev)
            dfs(idx, curr, time + t);
    }
}

int travelTime(int n, int m, int l, int A[], int B[], int T[]){
    
    for (int i = 0; i < m; i++){
        adjList[A[i]].push_back(make_pair(B[i], T[i]));
        adjList[B[i]].push_back(make_pair(A[i], T[i]));
    }
    
    int res = 0;
    for (int i = 0; i < n; i++){
        if (!visited[i]){
            maxNode = -1; d = -1;
            dfs(i, -1, 0);
            int A = maxNode;
            maxNode = -1; d = -1;
            dfs(A, -1, 0);
            int B = maxNode; res = max(res, d);
            ll currD = d, prevD = -1, curr = B;
            while(true){
                if (2*currD <= d)
                    break;
                for (int i = 0; i < adjList[curr].size(); i++){
                    int k = adjList[curr][i].first;
                    if (dist[k] < dist[curr]){
                        curr = k;
                        prevD = currD;
                        currD = dist[curr];
                        break;
                    }
                }
            }
            r.push_back(min(max(currD, d - currD), max(prevD, d - prevD)));
        }
    }
    sort(r.begin(), r.end());
    int k = r.size();
    if (k <= 1)
        return res;
    res = max(res, r[k - 1] + r[k - 2] + l);
    if (k > 2)
        res = max(res, r[k - 2] + r[k - 3] + 2*l);
        
    
    return res;
}

Compilation message (stderr)

dreaming.cpp: In function 'void dfs(int, int, int)':
dreaming.cpp:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < adjList[curr].size(); i++){
                     ~~^~~~~~~~~~~~~~~~~~~~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:60:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 for (int i = 0; i < adjList[curr].size(); i++){
                                 ~~^~~~~~~~~~~~~~~~~~~~~~

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