oj.uz

Submission #172269

# Submission time Handle Problem Language Result Execution time Memory
172269 2019-12-31T22:47:19 Z emil_physmath Hard route (IZhO17_road) C++17
19 / 100
 27 ms 24544 KB 
// #define DEBUG
#include <algorithm>
#include <vector>
#include <iostream>
#include <cstring>
#include <map>
using namespace std;
typedef long long llong;
const int maxN = 500005;

vector<int> nei[maxN];
pair<int, int> ray[maxN][3];
map<llong, llong> ans;
vector<int> dists[maxN];

namespace AC
{
    int n;
    pair<int, int> maxdist[maxN];
    bool used[maxN];

    void MaxDist(int u);
    pair<int, int> DFS(int u, int dep, int dist);
    void Solve(int n_)
    {
        n = n_;
        pair<int, int> ans(0, 0);
        for (int u=1; u<=n; u++)
            if (nei[u].size()==1)
            {
                memset(used+1, 0, n*sizeof(bool));
                MaxDist(u);
                memset(used+1, 0, n*sizeof(bool));
                pair<int, int> curAns=DFS(u, 0, 0);
                if (curAns.first>ans.first) ans=curAns;
                else if (curAns.first==ans.first) ans.second+=curAns.second;
            }
        cout<<ans.first<<' '<<ans.second/2<<'\n';
    }

    pair<int, int> DFS(int u, int dep, int dist)
    {
        used[u]=true;
        if (nei[u].size()==1 && used[nei[u][0]])
            return make_pair(dep*dist, 1);
        pair<int, int> ans(0, 0);
        for (int i=0; i<nei[u].size(); i++)
        {
            int to=nei[u][i];
            if (!used[to])
            {
                pair<int, int> curAns;
                if (maxdist[u].first==maxdist[to].first+1)
                    curAns=DFS(to, dep+1, max(dist, maxdist[u].second));
                else
                    curAns=DFS(to, dep+1, max(dist, maxdist[u].first));

                if (curAns.first>ans.first) ans=curAns;
                else if (curAns.first==ans.first) ans.second+=curAns.second;
            }
        }
        return ans;
    }

    void MaxDist(int u)
    {
        used[u]=true;
        maxdist[u]=make_pair(0, 0);
        if (nei[u].size()==1 && used[nei[u][0]]) return;
        for (int i=0; i<nei[u].size(); i++)
        {
            int to=nei[u][i];
            if (!used[to])
            {
                MaxDist(to);
                int temp=maxdist[to].first+1;
                if (temp>maxdist[u].first)
                {
                    swap(maxdist[u].first, maxdist[u].second);
                    maxdist[u].first=temp;
                }
                else if (temp>maxdist[u].second)
                    maxdist[u].second=temp;
            }
        }
    }
};
inline ostream& operator<<(ostream& ostr, const pair<int, int>& a)
{
    return ostr << "{" << a.first << ", " << a.second << "}";
}
void Maximize(pair<int, int>* a, pair<int, int> x)
{
    if (a[0].first == x.first)
        a[0].second += x.second;
    else if (a[1].first == x.first)
        a[1].second += x.second;
    else if (a[2].first == x.first)
        a[2].second += x.second;
    else if (x.first > a[2].first)
    {
        a[2] = x;
        sort(a, a + 3, greater<pair<int, int>>());
    }
}
void SetDown(int v, int par)
{
    fill(ray[v], ray[v] + 3, make_pair(0, 0));
    ray[v][0] = {0, 1};
    for (int to: nei[v])
        if (to != par)
        {
            SetDown(to, v);
            int val;
            Maximize(ray[v], {(val = ray[to][0].first + 1), ray[to][0].second/*1*/});
            if (val) dists[v].push_back(val);
        }
}
void SetUp(int v, int par)
{
    for (int to: nei[v])
        if (to != par)
        {
            // Set up[to].
            int val = 0;
            if (ray[v][0].first == ray[to][0].first + 1 && ray[v][0].second == ray[to][0].second)
                Maximize(ray[to], {(val = ray[v][1].first + 1), ray[v][1].second/*1*/});
            else if (ray[v][0].first == ray[to][0].first + 1)
                Maximize(ray[to], {(val = ray[v][0].first + 1), ray[v][0].second - ray[to][0].second/*1*/});
            else
                Maximize(ray[to], {(val = ray[v][0].first + 1), ray[v][0].second});
            if (val) dists[to].push_back(val);
            SetUp(to, v);
        }
    sort(dists[v].begin(), dists[v].end(), greater<int>());
#ifdef DEBUG
    cerr << "v: " << v << "\tdists: " << dists[v][0] << ' ';
    if (dists[v].size() >= 2) cout << dists[v][1];
    if (dists[v].size() >= 3) cout << ' ' << dists[v][2];
    cout << endl;
#endif
    if (dists[v].size() < 3) return;
    bool eq = (dists[v][1] == dists[v][2]);
    int cnt[2];
    for (int i = 0; i < 3; ++i)
    {
        if (ray[v][i].first == dists[v][1])
            cnt[0] = ray[v][i].second;
        if (ray[v][i].first == dists[v][2])
            cnt[1] = ray[v][i].second;
    }
    if (eq)
        ans[dists[v][0] * (dists[v][1] + dists[v][2])] += (cnt[0] * (cnt[0] - 1LL)) / 2LL;
    else
        ans[dists[v][0] * (dists[v][1] + dists[v][2])] += (llong)cnt[0] * cnt[1];
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    int n;
    // cin >> n;
    // n = rand() % 20 + 1;
    cin >> n;
    /*int seed;
    cin >> seed;
    srand(seed);
    cerr << n << endl;*/
    for (int i = 1; i < n; ++i)
    {
        int u, v;
        cin >> u >> v;
        /*v = i + 1;
        u = rand() % i + 1;
        cerr << u << ' ' << v << endl;*/
        nei[u].push_back(v);
        nei[v].push_back(u);
    }
    SetDown(1, -1);
    /*for (int v = 1; v <= n; ++v)
        cerr << v << ": " << ray[v][0] << ' ' << ray[v][1] << ' ' << ray[v][2] << endl;*/
    SetUp(1, -1);
    #ifdef DEBUG
    for (int v = 1; v <= n; ++v)
    {
        cerr << v << ": " << ray[v][0] << ' ' << ray[v][1] << ' ' << ray[v][2] << endl;
    }
    for (auto it: ans)
        cerr << it << endl;
    #endif
    if (ans.size())
        cout << ans.rbegin()->first << ' ' << ans.rbegin()->second;
    else
        cout << "0 1";
    // cout << endl;
    // AC::Solve(n);
}
/*
8
1 2
1 3
1 4
2 5
4 6
1 7
2 8

6 5
6 7 // right answer
*/

Compilation message

road.cpp: In function 'std::pair<int, int> AC::DFS(int, int, int)':
road.cpp:47:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=0; i<nei[u].size(); i++)
                       ~^~~~~~~~~~~~~~
road.cpp: In function 'void AC::MaxDist(int)':
road.cpp:70:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=0; i<nei[u].size(); i++)
                       ~^~~~~~~~~~~~~~
road.cpp: In function 'void SetUp(int, int)':
road.cpp:155:80: warning: 'cnt[1]' may be used uninitialized in this function [-Wmaybe-uninitialized]
         ans[dists[v][0] * (dists[v][1] + dists[v][2])] += (llong)cnt[0] * cnt[1];
                                                                           ~~~~~^
road.cpp:155:59: warning: 'cnt[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
         ans[dists[v][0] * (dists[v][1] + dists[v][2])] += (llong)cnt[0] * cnt[1];
                                                           ^~~~~~~~~~~~~

Subtask #1
19.0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 23 ms 23800 KB Output is correct
3 Correct 23 ms 23800 KB Output is correct
4 Correct 23 ms 23800 KB Output is correct
5 Correct 23 ms 23800 KB Output is correct
6 Correct 23 ms 23804 KB Output is correct
7 Correct 23 ms 23808 KB Output is correct
8 Correct 23 ms 23804 KB Output is correct
9 Correct 23 ms 23800 KB Output is correct
10 Correct 24 ms 23888 KB Output is correct
11 Correct 23 ms 23800 KB Output is correct
12 Correct 23 ms 23800 KB Output is correct
13 Correct 23 ms 23800 KB Output is correct
14 Correct 23 ms 23804 KB Output is correct
15 Correct 23 ms 23800 KB Output is correct
16 Correct 23 ms 23800 KB Output is correct
17 Correct 23 ms 23800 KB Output is correct
18 Correct 23 ms 23800 KB Output is correct
19 Correct 23 ms 23928 KB Output is correct
20 Correct 22 ms 23800 KB Output is correct
21 Correct 23 ms 23800 KB Output is correct
22 Correct 22 ms 23800 KB Output is correct
23 Correct 23 ms 23800 KB Output is correct
24 Correct 23 ms 23800 KB Output is correct

Subtask #2
0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 23 ms 23800 KB Output is correct
3 Correct 23 ms 23800 KB Output is correct
4 Correct 23 ms 23800 KB Output is correct
5 Correct 23 ms 23800 KB Output is correct
6 Correct 23 ms 23804 KB Output is correct
7 Correct 23 ms 23808 KB Output is correct
8 Correct 23 ms 23804 KB Output is correct
9 Correct 23 ms 23800 KB Output is correct
10 Correct 24 ms 23888 KB Output is correct
11 Correct 23 ms 23800 KB Output is correct
12 Correct 23 ms 23800 KB Output is correct
13 Correct 23 ms 23800 KB Output is correct
14 Correct 23 ms 23804 KB Output is correct
15 Correct 23 ms 23800 KB Output is correct
16 Correct 23 ms 23800 KB Output is correct
17 Correct 23 ms 23800 KB Output is correct
18 Correct 23 ms 23800 KB Output is correct
19 Correct 23 ms 23928 KB Output is correct
20 Correct 22 ms 23800 KB Output is correct
21 Correct 23 ms 23800 KB Output is correct
22 Correct 22 ms 23800 KB Output is correct
23 Correct 23 ms 23800 KB Output is correct
24 Correct 23 ms 23800 KB Output is correct
25 Correct 27 ms 24440 KB Output is correct
26 Incorrect 27 ms 24544 KB Output isn't correct
27 Halted 0 ms 0 KB -

Subtask #3
0 / 48.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 23 ms 23800 KB Output is correct
3 Correct 23 ms 23800 KB Output is correct
4 Correct 23 ms 23800 KB Output is correct
5 Correct 23 ms 23800 KB Output is correct
6 Correct 23 ms 23804 KB Output is correct
7 Correct 23 ms 23808 KB Output is correct
8 Correct 23 ms 23804 KB Output is correct
9 Correct 23 ms 23800 KB Output is correct
10 Correct 24 ms 23888 KB Output is correct
11 Correct 23 ms 23800 KB Output is correct
12 Correct 23 ms 23800 KB Output is correct
13 Correct 23 ms 23800 KB Output is correct
14 Correct 23 ms 23804 KB Output is correct
15 Correct 23 ms 23800 KB Output is correct
16 Correct 23 ms 23800 KB Output is correct
17 Correct 23 ms 23800 KB Output is correct
18 Correct 23 ms 23800 KB Output is correct
19 Correct 23 ms 23928 KB Output is correct
20 Correct 22 ms 23800 KB Output is correct
21 Correct 23 ms 23800 KB Output is correct
22 Correct 22 ms 23800 KB Output is correct
23 Correct 23 ms 23800 KB Output is correct
24 Correct 23 ms 23800 KB Output is correct
25 Correct 27 ms 24440 KB Output is correct
26 Incorrect 27 ms 24544 KB Output isn't correct
27 Halted 0 ms 0 KB -