Submission #347931

#	Time	Username	Problem	Language	Result	Execution time	Memory
347931		training4usaco	Traffic (IOI10_traffic)	C++11	100 / 100	1171 ms	174976 KiB

traffic

#include "traffic.h"
#include <climits>
#include <iostream>
#include <vector>
using namespace std;

int n;
vector<int> p;

vector<vector<int>> adj;
vector<int> traffic;
vector<int> children;

int numFans = 0;

void dfs (int idx, int par) {
    for (int i = 0; i < adj[idx].size(); ++i) {

        if (adj[idx][i] == par) {
            continue;
        }

        dfs(adj[idx][i], idx);
        children[idx] += children[adj[idx][i]];
        traffic[idx] = max(traffic[idx], children[adj[idx][i]]);
    }

    traffic[idx] = max(traffic[idx], numFans - children[idx] - p[idx]);

    children[idx] += p[idx];
}

int LocateCentre (int ni, int pi[], int d[], int s[]) {
    n = ni;

    p = vector<int>(n);

    for(int i = 0; i < n; ++i) {
        p[i] = pi[i];
    }

    adj = vector<vector<int>>(n);
    traffic = vector<int>(n);
    children = vector<int>(n);

    for (int i = 0; i < n; i++) {
        numFans += p[i];
    }

    for (int i = 0; i < n - 1; i++) {
        adj[s[i]].push_back(d[i]);
        adj[d[i]].push_back(s[i]);
    }

    dfs(0, -1);

    int best = INT_MAX;
    int ans = -1;

    for (int i = 0; i < n; i++) {
        if (traffic[i] < best) {
            ans = i;
            best = traffic[i];
        }
    }

    return ans;
}

Compilation message (stderr)

traffic.cpp: In function 'void dfs(int, int)':
traffic.cpp:17:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |     for (int i = 0; i < adj[idx].size(); ++i) {
      |                     ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 25 / 25
• Subtask 3: 25 / 25
• Subtask 4: 25 / 25