Submission #212589

#	Time	Username	Problem	Language	Result	Execution time	Memory
212589		toxic_hack	Mag (COCI16_mag)	C++14	120 / 120	1770 ms	262144 KiB

mag

// g++ -std=c++14

/*

Today might be the chance to grasp the chance to let your talent bloom.
May be tomorrow, the day after, or next year...
May be even when you are 30. I'm not sure if physique has anything to do with it
but if you think that it will never come, it probably never will.

- Tooru Oikawa.

*/
#include<bits/stdc++.h>

typedef long long ll;
typedef long double lld;
using namespace std;

#define endl "\n"
#define fi first
#define se second
#define pb(x) push_back(x)
#define mp(x,y) make_pair(x,y)
#define MEMS(a,b) memset(a,b,sizeof(a))
#define _ ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define __ freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);
#define all(c) c.begin(),c.end()
#define pii pair<int, int>
#define tr(...) cout<<__FUNCTION__<<' '<<__LINE__<<" = ";trace(#__VA_ARGS__, __VA_ARGS__)
template<typename S, typename T>
ostream& operator<<(ostream& out,pair<S,T> const& p){out<<'('<<p.fi<<", "<<p.se<<')';return out;}

template<typename T>
ostream& operator<<(ostream& out,vector<T> const& v){
ll l=v.size();for(ll i=0;i<l-1;i++)out<<v[i]<<' ';if(l>0)out<<v[l-1];return out;}

template <typename T>
ostream &operator<<(ostream &out, set<T> const &v) {
    for (auto i = v.begin(); i != v.end(); i++)
        out << (*i) << ' ';
    return out;
}
template <typename T, typename V>
ostream &operator<<(ostream &out, map<T, V> const &v) {
    for (auto i = v.begin(); i != v.end(); i++)
        out << "\n" << (i->first) <<  ":"  << (i->second);
    return out;
}

template<typename T>
void trace(const char* name, T&& arg1){cout<<name<<" : "<<arg1<<endl;}

template<typename T, typename... Args>
void trace(const char* names, T&& arg1, Args&&... args){
const char* comma = strchr(names + 1, ',');cout.write(names, comma-names)<<" : "<<arg1<<" | ";trace(comma+1,args...);}

// #define int ll

const int N = 1e6 + 100;

int n;
vector<int> g[N];
int arr[N];

int dp_down[N], dp_up[N];
int parent[N];
int ans0 = 0;

void setabc(int &a, int &b, int c) {
    if (c > a) {
        b = a;
        a = c;
    } else if (c > b) {
        b = c;
    }
}

void dfs0(int v, int p) {
     parent[v] = p;
    int curr = (arr[v] == 1);
    int a = 0, b = 0;
    for (auto u : g[v]) {
        if (u == p)  continue;
        dfs0(u, v);
        curr = max(curr, dp_down[u] + 1);
        setabc(a, b, dp_down[u]);
    }
    if (arr[v] == 1) {
        dp_down[v] = curr;
        ans0 = max(ans0, a + b + 1);
    }
}

void dfs1(int v, int p, int mx_len = 0) {
    // tr(v, mx_len);
    dp_up[v] = mx_len;
    if (arr[v] == 1) {
        multiset<int> child;
        child.insert(mx_len);
        for (auto u : g[v]) {
            if (u == p) continue;
            child.insert(dp_down[u]);
        }

        for (auto u : g[v]) {
            if (u == p) continue;
            child.erase(child.find(dp_down[u]));
            int heremx = *child.rbegin() + 1;
            dfs1(u, v, heremx);
            child.insert(dp_down[u]);
        }

    } else {
        for (auto u : g[v]) {
            if (u == p) continue;
            dfs1(u, v, 0);
        }
    }
}

int cmp(int a, int b, int c, int d) {
    return (1LL * a * d < 1LL * c * b);
}

const int inf = 1e9 + 1;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r)
{
	uniform_int_distribution<int> uid(l, r);
	return uid(rng);
}


void gen() {
    n = rand(1e5, 1e5);
    // vector<int> curr = {0};
    // vector<int> parent(n + 1);
    // for (int i = 1; i <= n; i++) {
    //     int kk = curr.size();
    //     // int p = curr[rand(0, kk - 1)];
    //     int p = curr.back();
    //     parent[i] = p;
    //     curr.push_back(i);
    //     if (i > 1) {
    //         g[parent[i]].push_back(i);
    //         g[i].push_back(parent[i]);
    //     }
    // }
    for (int i = 2; i <= n; i++) {
        g[i].push_back(i - 1);
        g[i - 1].push_back(i);
    }
    for (int i = 1; i <= n; i++) {
        int temp = rand(1, 10);
        if (temp > 5) {
            arr[i] = rand(1, 1e9);
        } else {
            arr[i] = 1;
        }
        // arr[i] = rand(1, 1);
    }
    // tr(n);
    cout << n << endl;
}

int solve() {
    cin >> n;
    for (int i = 0; i < n - 1; i++) {
        int v, u;
        cin >> v >> u;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    for (int i = 1; i <= n; i++) {
        cin >> arr[i];
    }
    // gen();
    dfs0(1, 0);
    dfs1(1, 0);

    if (ans0 == 0) {
        int mi = inf;
        for (int i = 1; i <= n; i++) {
            mi = min(mi, arr[i]);
        }
        cout << mi << "/1" << endl;
    } else {
        int a = 1, b = ans0;
        for (int i = 1; i <= n; i++) {
            vector<int> pth;
            for (auto j : g[i]) {
                if (j == parent[i]) continue;
                pth.push_back(dp_down[j]);
            }
            pth.push_back(dp_up[i]);
            sort(all(pth));
            reverse(all(pth));
            // tr(i, pth, a, b);
            if ((int)pth.size() == 1) {
                int c = arr[i], d = pth[0] + 1;
                if (!cmp(a, b, c, d)) {
                    a = c, b = d;
                }
            } else {
                int c = arr[i], d = 1 + pth[0] + pth[1];
                if (!cmp(a, b, c, d)) {
                    a = c, b = d;
                }
            }
        }
        assert(b != 0 && a != 0);
        int g = __gcd(a, b);
        a /= g;
        b /= g;
        cout << a << "/" << b << endl;
    }
    return 0;
}

int32_t main(){ 
    int t;
    // cin >> t;
    t = 1;
    while (t--) solve();
}

• Subtask 1: 12 / 12
• Subtask 2: 12 / 12
• Subtask 3: 12 / 12
• Subtask 4: 12 / 12
• Subtask 5: 12 / 12
• Subtask 6: 12 / 12
• Subtask 7: 12 / 12
• Subtask 8: 12 / 12
• Subtask 9: 12 / 12
• Subtask 10: 12 / 12