Submission #93239

#	Time	Username	Problem	Language	Result	Execution time	Memory
93239		SamAnd	Hard route (IZhO17_road)	C++17	0 / 100	2 ms	376 KiB

road

#include <bits/stdc++.h>
using namespace std;
const int N = 5003;

int n;
vector<int> a[N];

int ans[N][N];

int d[N], maxd[N];;
void dfs0(int x, int p)
{
    if (x == p)
        d[x] = 0;
    else
        d[x] = d[p] + 1;
    maxd[x] = d[x];
    for (int i = 0; i < a[x].size(); ++i)
    {
        int h = a[x][i];
        if (h == p)
            continue;
        dfs0(h, x);
        maxd[x] = max(maxd[x], maxd[h]);
    }
}

void dfs(int x, int p, int dd, int pp)
{
    multiset<int> s;
    for (int i = 0; i < a[x].size(); ++i)
    {
        int h = a[x][i];
        if (h == p)
            continue;
        s.insert(maxd[h] - d[x]);
    }
    for (int i = 0; i < a[x].size(); ++i)
    {
        int h = a[x][i];
        if (h == p)
            continue;
        s.erase(s.find(maxd[h] - d[x]));
        if (s.empty())
            dfs(h, x, dd, pp);
        else
            dfs(h, x, max(dd, *(--s.end())), pp);
        s.insert(maxd[h] - d[x]);
    }
    ans[pp][x] = dd * d[x];
}

int main()
{
    freopen("input2.txt", "r", stdin);
    cin >> n;
    for (int i = 0; i < n - 1; ++i)
    {
        int x, y;
        cin >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    for (int x = 1; x <= n; ++x)
    {
        if (a[x].size() == 1)
        {
            if (x == 6)
                cout << "";
            dfs0(x, x);
            dfs(x, x, 0, x);
        }
    }
    int maxu = -1;
    for (int x = 1; x <= n; ++x)
    {
        if (a[x].size() > 1)
            continue;
        for (int y = 1; y <= n; ++y)
        {
            if (a[y].size() > 1)
                continue;
            maxu = max(maxu, ans[x][y]);
        }
    }
    int q = 0;
    for (int x = 1; x <= n; ++x)
    {
        if (a[x].size() > 1)
            continue;
        for (int y = 1; y <= n; ++y)
        {
            if (a[y].size() > 1)
                continue;
            if (ans[x][y] == maxu)
                ++q;
        }
    }
    cout << maxu << ' ' << q << endl;
    return 0;
}

Compilation message (stderr)

road.cpp: In function 'void dfs0(int, int)':
road.cpp:18:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < a[x].size(); ++i)
                     ~~^~~~~~~~~~~~~
road.cpp: In function 'void dfs(int, int, int, int)':
road.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < a[x].size(); ++i)
                     ~~^~~~~~~~~~~~~
road.cpp:38:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < a[x].size(); ++i)
                     ~~^~~~~~~~~~~~~
road.cpp: In function 'int main()':
road.cpp:55:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     freopen("input2.txt", "r", stdin);
     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 19
• Subtask 2: 0 / 33
• Subtask 3: 0 / 48