Submission #1126711

#	Time	Username	Problem	Language	Result	Execution time	Memory
1126711		DaciejMaciej	Hard route (IZhO17_road)	C++20	0 / 100	87 ms	74640 KiB

road

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// #include <ext/rope>

using namespace std;
// using namespace __gnu_pbds;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef long double ld;

template <class T>

using VV = vector<vector<T>>;

using VI = vector<int>;
using VVI = vector<vector<int>>;

using VL = vector<long long>;
using VVL = vector<vector<long long>>;

using VC = vector<char>;
using VVC = vector<vector<char>>;

using VB = vector<bool>;
using VVB = vector<vector<bool>>;

using VD = vector<double>;
using VVD = vector<vector<double>>;

using PII = pair<int, int>;
using PLL = pair<long long, long long>;
using PIL = pair<int, long long>;
using PLI = pair<long long, int>;

using VPII = vector<pair<int, int>>;
using VPLL = vector<pair<long long, long long>>;

#define LINE '\n'
#define SPACE ' '
#define PB push_back
#define FOR(i, a, b) for (int i = (a); i < (int(b)); i++)
#define FORE(i, a, b) for (int i = (a); i <= (int)((b)); i++)
#define ALL(x) x.begin(), x.end()
#define RALL(x) x.rbegin(), x.rend()
#define sq(a) ((a) * (a))
#define sz(x) ((int)x.size())

#define fastio()                      \
    ios_base::sync_with_stdio(false); \
    cin.tie(nullptr);                 \
    cout.tie(nullptr)
#define debug(x) cerr << #x << " = " << x << endl;

const ll MOD = 1e9 + 7;

template <class T>
inline void maxi(T &a, T b)
{
    a = max(a, b);
}

template <class T>
inline void mini(T &a, T b)
{
    a = min(a, b);
}

template <class T>
inline void addi(T &a, T b)
{
    a = (a + b) % MOD;
}

template <class T>
inline void subi(T &a, T b)
{
    a = (a - b + MOD) % MOD;
}

template <class T>
inline T add(T a, T b)
{
    return (a + b) % MOD;
}

template <class T>
inline T sub(T a, T b)
{
    return (a - b + MOD) % MOD;
}

template <class T>
inline T mul(T a, T b)
{
    return ((a % MOD) * (b % MOD)) % MOD;
}

constexpr ll binpow(ll a, ll b, ll mod)
{
    ll res = 1;
    while (b > 0)
    {
        if (b & 1)
        {
            res = (res * a) % mod;
        }
        a = (a * a) % mod;
        b >>= 1;
    }

    return res;
}

const int INF = 1e9;

const int MAX_N = 5e5 + 3;

int n;
VVL dp(MAX_N, VL(2, 0)); // 0 - best, 1 - second best
VL dp2(MAX_N, 0);        // best up the tree

VVL dp_ways(MAX_N, VL(2, 1));
VL dp2_ways(MAX_N, 1);

VI g[MAX_N];

void dfs1(int c, int p)
{
    for (auto v : g[c])
    {
        if (v == p)
            continue;
        dfs1(v, c);

        if (dp[v][0] + 1 == dp[c][1]) 
        {
            dp_ways[c][1] = dp_ways[v][0];
            continue;
        }

        if (dp[v][0] + 1 > dp[c][1])
        {
            dp[c][1] = dp[v][0] + 1;
            dp_ways[c][1] = dp_ways[v][0];
        }
        if (dp[c][0] < dp[c][1] || 
            (dp[c][0] == dp[c][1] && dp_ways[c][0] < dp_ways[c][1]))
        {
            swap(dp[c][0], dp[c][1]);
            swap(dp_ways[c][0], dp_ways[c][1]);
        }
    }
}

ll ans = 0;
ll ans_ways = 0;
void dfs2(int c, int p)
{
    if (sz(g[c]) >= 3)
    {
        VPLL vec = {{dp[c][0], dp_ways[c][0]},
                    {dp[c][1], dp_ways[c][1]},
                    {dp2[c], dp2_ways[c]}};

        sort(RALL(vec));

        ll t = vec[0].first * (vec[1].first + vec[2].first);
        ll t_w = vec[0].second *vec[1].second *vec[2].second;

        if(vec[0].first == vec[1].first && vec[1].first == vec[2].first) {
            t_w *= 3;
        }
        else if(vec[0].first == vec[1].first) {
            t_w *= 2;
        }
        
        if(t > ans) {
            ans = t;
            ans_ways = t_w;
        }
        else if(t == ans) {
            ans_ways += t_w;
        }
        
    }

    for (auto v : g[c])
    {
        if (v == p)
            continue;

        dp2[v] = dp2[c] + 1;
        if (dp[v][0] + 1 == dp[c][0])
        { // use second best
            dp2[v] = dp[c][1] + 1;
            dp2_ways[v] = dp_ways[c][1];
        }
        else
        {
            dp2[v] = dp[c][0] + 1;
            dp2_ways[v] = dp_ways[c][0];
        }

        dfs2(v, c);
    }
}

void solve()
{
    cin >> n;
    FOR(i, 0, n - 1)
    {
        int a, b;
        cin >> a >> b;
        a--, b--;
        g[a].PB(b);
        g[b].PB(a);
    }

    dfs1(0, 0);
    dfs2(0, 0);

    if(ans == 0) ans_ways = 1;
    cout << ans <<  SPACE << ans_ways << LINE;
}

int main()
{
    fastio();

    int t = 1;
    // cin >> t;

    while (t--)
        solve();
}

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