Submission #991112

#	Time	Username	Problem	Language	Result	Execution time	Memory
991112		borisAngelov	Traffic (IOI10_traffic)	C++17	100 / 100	821 ms	198096 KiB

traffic

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

using namespace std;

const int maxn = 1000005;
const long long inf = (1LL << 62);

int n;
int a[maxn];

vector<int> g[maxn];

long long subtreeSum[maxn];
long long down[maxn];
long long prv[maxn];
long long ans[maxn];

void dfsInit(int node, int par)
{
    subtreeSum[node] = a[node];
    down[node] = 0;

    for (int i = 0; i < g[node].size(); ++i)
    {
        if (g[node][i] != par)
        {
            dfsInit(g[node][i], node);
            subtreeSum[node] += subtreeSum[g[node][i]];
            down[node] = max(down[node], subtreeSum[g[node][i]]);
        }
    }

    prv[node] = down[node];
}

void dfsSolve(int node, int par)
{
    ans[node] = down[node];

    for (int i = 0; i < g[node].size(); ++i)
    {
        int to = g[node][i];

        if (to != par)
        {
            subtreeSum[node] -= subtreeSum[to];
            subtreeSum[to] += subtreeSum[node];
            down[to] = max(down[to], subtreeSum[node]);

            dfsSolve(to, node);

            down[to] = prv[to];
            subtreeSum[to] -= subtreeSum[node];
            subtreeSum[node] += subtreeSum[to];
        }
    }
}

int LocateCentre(int N, int pp[], int S[], int D[])
{
    n = N;

    for (int i = 1; i <= n; ++i)
    {
        a[i] = pp[i - 1];
    }

    for (int i = 1; i <= n - 1; ++i)
    {
        int x = S[i - 1];
        int y = D[i - 1];

        ++x;
        ++y;

        g[x].push_back(y);
        g[y].push_back(x);
    }

    dfsInit(1, -1);
    dfsSolve(1, -1);

    long long big = inf;
    int node = -1;

    for (int i = 1; i <= n; ++i)
    {
        //cout << i << " :: " << ans[i] << endl;

        if (big > ans[i])
        {
            big = ans[i];
            node = i;
        }
    }

    //cout << big << endl;

    return node - 1;
}

Compilation message (stderr)

traffic.cpp: In function 'void dfsInit(int, int)':
traffic.cpp:24:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |     for (int i = 0; i < g[node].size(); ++i)
      |                     ~~^~~~~~~~~~~~~~~~
traffic.cpp: In function 'void dfsSolve(int, int)':
traffic.cpp:41:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     for (int i = 0; i < g[node].size(); ++i)
      |                     ~~^~~~~~~~~~~~~~~~

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