Submission #76654

#	Time	Username	Problem	Language	Result	Execution time	Memory
76654		Shafin666	Dreaming (IOI13_dreaming)	C++14	18 / 100	65 ms	12280 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"

#define edge pair<int, int>
#define to first
#define cost second
using namespace std;

const int MAX_N = 123456;
vector<edge> adj[MAX_N]; vector<int> R;
bool visited[MAX_N];
int maxdist, point;
edge parent[MAX_N];

void dfs1(int u, int par, int val) {
    int i, mx = 0;

    if(val > maxdist) {
        maxdist = val;
        point = u;
    }

    for(i = 0; i < (int) adj[u].size(); i++) {
        edge v = adj[u][i];
        if(v.to == par) continue;

        dfs1(v.to, u, v.cost + val);
    }
}

void dfs2(int u, int par, int val) {
    visited[u] = 1;
    int i, mx = 0;

    if(val > maxdist) {
        maxdist = val;
        point = u;
    }

    for(i = 0; i < (int) adj[u].size(); i++) {
        edge v = adj[u][i];
        if(v.to == par) continue;

        parent[v.to] = edge(u, v.cost);
        dfs2(v.to, u, val+v.cost);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    int i, ans = 0, j;

    for(i = 0; i < M; i++) {
        adj[A[i]].push_back(edge(B[i], T[i]));
        adj[B[i]].push_back(edge(A[i], T[i]));
    }

    for(i = 0; i < N; i++) {
        if(visited[i]) continue; 
        maxdist = -1; dfs1(i, i, 0); int one = point; 
        maxdist = -1; dfs2(one, one, 0); int two = point;
        
        ans = max(ans, maxdist);

        int able = maxdist/2, d = 0;

        for(j = two; j != one; j = parent[i].to) {
            if(d + parent[j].cost > able) {
                d = min(d + parent[j].cost, maxdist-d);
                break;
            } d += parent[j].cost;
        } R.push_back(d);
    } sort(R.begin(), R.end(), greater<int>());

    if(R.size() > 1) ans = max(ans, R[0]+L+R[1]);
    if(R.size() > 2) ans = max(ans, R[1]+L+L+R[2]);

    return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'void dfs1(int, int, int)':
dreaming.cpp:16:12: warning: unused variable 'mx' [-Wunused-variable]
     int i, mx = 0;
            ^~
dreaming.cpp: In function 'void dfs2(int, int, int)':
dreaming.cpp:33:12: warning: unused variable 'mx' [-Wunused-variable]
     int i, mx = 0;
            ^~

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