Submission #246299

#	Time	Username	Problem	Language	Result	Execution time	Memory
246299		Vladikus004	Mag (COCI16_mag)	C++14	120 / 120	674 ms	239756 KiB

mag

#include <bits/stdc++.h>
#define int long long
//#pragma comment(linker, "/STACK:6666777216")
#define inf 2e9
#define all(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair <int, int> pii;

const int N = 1000000 + 3;
int n, z[N], p[N], udp[N], ddp[N];
vector <vector <int> > v, mx;

void udfs(int x){
    p[x] = 1;
//    cout << x << " " << v[x].size() << "\n";
//    cout << p[v[x][0]] << " " << p[v[x][1]] << "!!!\n";
//    if ( x == 432518) {
//        exit(0);
//    }
    for (auto u: v[x]){
        if (p[u]) continue;
        udfs(u);
        mx[x].push_back(udp[u]);
        udp[x] = max(udp[x], udp[u]);
    }
    if (z[x] == 1) udp[x]++;
    else udp[x] = 0;
    if (mx[x].size()){
    sort(all(mx[x]));
    reverse(all(mx[x]));
    }
}

int ans;
int e_ans;
int mn = inf * inf;

void ddfs(int x, int way){
    p[x] = 1;
    mn = min(mn, z[x]);
    e_ans = max(e_ans, way);
    if (z[x] == 2){
        if (!mx[x].empty()){
        vector <int> buff;
        buff.push_back(way);
        buff.push_back(mx[x][0]);
        if (mx[x].size() > 1)
        buff.push_back(mx[x][1]);
        sort(all(buff));
        ans = max(ans, buff[(buff.size() - 1) / 2] * 2 + 1);
        }
    }
    for (auto u: v[x]){
        if (p[u]) continue;
        if (z[x] != 1) {
            ddfs(u, 0);
            continue;
        }
        e_ans = max(e_ans, udp[u]);
        if (udp[u] == mx[x][0]){
            if (mx[x].size() > 1)
            ddfs(u, max(way + 1, mx[x][1] + 1));
            else ddfs(u, way + 1);
        }else{
            ddfs(u, max(way + 1, mx[x][0] + 1));
        }
    }
    if (mx[x].size()){
    int t = mx[x][0];
    if (mx[x].size() > 1) t += mx[x][1];
    if (z[x] == 1) e_ans = max(e_ans, t + 1);
    }
}

int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    #ifdef LOCAL
        freopen("input.txt", "r", stdin);
    #endif // LOCAL
    cin >> n;
    v.resize(n);
    mx.resize(n);
    for (int i = 0; i < n - 1; i++){
        int a, b;
        cin >> a >> b;
        --a; --b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for (int i = 0; i < n; i++) cin >> z[i];
    udfs(0);
    memset(p, 0, sizeof p);
    ddfs(0, 0);
//    assert(ans != 799997);
    if (ans){
        if (e_ans * 2 < ans)
            cout << "2/"<<ans;
        else
            cout << "1/"<<e_ans;
    }else
    if (e_ans){
        cout << "1/"<<e_ans;
    }else
        cout << mn<<"/1";
}

• 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