Submission #1110035

#	Time	Username	Problem	Language	Result	Execution time	Memory
1110035		Whisper	Hard route (IZhO17_road)	C++17	100 / 100	524 ms	115620 KiB

road

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define REPD(i, a) for (int i = (a) - 1; i >= 0; --i)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)


constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

/*
    Phu Trong from Nguyen Tat Thanh High School for gifted student
*/

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
#define MAX                     500005
vector<pair<int, int>> G[MAX];

int numNode;

struct DP{
    int max_value, cnt;
    DP():max_value(0), cnt(1){}
    DP(int _max_value, int _cnt): max_value(_max_value), cnt(_cnt){}
};

DP combine(DP a, DP b){
    if(a.max_value > b.max_value) return a;
    if(a.max_value < b.max_value) return b;
    return DP(a.max_value, a.cnt + b.cnt);
}
DP res;
DP dp[MAX];

void dfs(int u, int p = -1){
    for (pair<int, int>&x : G[u]){
        int v = x.first;
        if(v ^ p){
            dfs(v, u);
            dp[u] = combine(dp[u], DP(dp[v].max_value + 1, dp[v].cnt));
        }
    }
}

void reroot(int u, int p = -1){
    sort(G[u].begin(), G[u].end(), [&](const pair<int, int>&a, const pair<int, int>&b){
        return dp[a.first].max_value > dp[b.first].max_value;
    });
    if((int)G[u].size() >= 3){
        int node[3];
        node[0] = dp[G[u][0].first].max_value + 1, node[1] = dp[G[u][1].first].max_value + 1, node[2] = dp[G[u][2].first].max_value + 1;
        DP cand = DP(node[0] * (node[1] + node[2]), 0);
        int sum = 0;
        for (pair<int, int>&x : G[u]) {
            int v = x.first;
            if(dp[v].max_value + 1 == node[2]) cand.cnt += sum * dp[v].cnt;
            if(dp[v].max_value + 1 == node[1]) sum += dp[v].cnt;
        }
        res = combine(res, cand);
    }
    DP mx[2];
    mx[1] = DP(0, 0);
    for (pair<int, int>&x : G[u]) {
        int v = x.first;
        if(dp[v].max_value + 1 > mx[0].max_value){
            mx[1] = mx[0];
            mx[0] = DP(dp[v].max_value + 1, dp[v].cnt);
        }
        else if(dp[v].max_value + 1 == mx[0].max_value) mx[0].cnt += dp[v].cnt;
        else if(dp[v].max_value + 1 > mx[1].max_value) mx[1] = DP(dp[v].max_value + 1, dp[v].cnt);
        else if(dp[v].max_value + 1 == mx[1].max_value) mx[1].cnt += dp[v].cnt;
    }

    DP rem = dp[u];
    for (pair<int, int>&x : G[u]) {
        int v = x.first;
        if(v ^ p){
            dp[u] = mx[0];
            if(dp[v].max_value + 1 == dp[u].max_value){
                if(dp[v].cnt == dp[u].cnt){
                    dp[u] = mx[1];
                }
                else{
                    dp[u].cnt -= dp[v].cnt;
                }
            }
            reroot(v, u);
        }
    }
    dp[u] = rem;
}

void process(void){
    cin >> numNode;
    for (int i = 1; i < numNode; ++i){
        int u, v; cin >> u >> v;
        G[u].emplace_back(v, 1);
        G[v].emplace_back(u, 1);
    }
    dfs(1);
    reroot(1);
    cout << res.max_value << " " << res.cnt;
}
signed main(){
    #define name "Whisper"
    cin.tie(nullptr) -> sync_with_stdio(false);
    //freopen(name".inp", "r", stdin);
    //freopen(name".out", "w", stdout);
    process();
    return (0 ^ 0);
}

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