Submission #696239

#	Time	Username	Problem	Language	Result	Execution time	Memory
696239		bachhoangxuan	Mag (COCI16_mag)	C++17	120 / 120	453 ms	180872 KiB

mag

// Judges with GCC >= 12 only needs Ofast
// #pragma GCC optimize("O3,no-stack-protector,fast-math,unroll-loops,tree-vectorize")
// MLE optimization
// #pragma GCC optimize("conserve-stack")
// Old judges
// #pragma GCC target("sse4.2,popcnt,lzcnt,abm,mmx,fma,bmi,bmi2")
// New judges. Test with assert(__builtin_cpu_supports("avx2"));
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
// Atcoder
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma")
#include<bits/stdc++.h>
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
uniform_real_distribution<> pp(0.0,1.0);
#define int long long
#define ld long double
#define pii pair<int,int>
#define piii pair<int,pii>
#define fi first
#define se second
const int inf=1e18;
const int mod=998244353;
const int mod2=1e9+7;
const int maxn=1000005;
const int maxq=500005;
const int maxl=20;
const int maxa=1000005;
int power(int a,int n){
    int res=1;
    while(n){
        if(n&1) res=res*a%mod;
        a=a*a%mod;n>>=1;
    }
    return res;
}
int dep[maxn],c[maxn],n,ans,p,q;
vector<int> edge[maxn];
void dfs(int u,int par){
    int Max1=0,Max2=0;
    if(c[u]==1) dep[u]=1;
    for(int v:edge[u]){
        if(v==par) continue;
        dfs(v,u);
        if(c[u]==1){
            dep[u]=max(dep[u],dep[v]+1);
            if(dep[v]>Max1){Max2=Max1;Max1=dep[v];}
            else if(dep[v]>Max2) Max2=dep[v];
        }
    }
    if(c[u]==1){
        ans=max(ans,dep[u]);
        ans=max(ans,Max1+Max2+1);
    }
}
void redfs(int u,int par,int len){
    int Max1=0,Max2=0;
    for(int v:edge[u]){
        if(v==par) continue;
        if(dep[v]>Max1){Max2=Max1;Max1=dep[v];}
        else if(dep[v]>Max2) Max2=dep[v];
    }
    if(len>Max1){Max2=Max1;Max1=len;}
    else if(len>Max2) Max2=len;
    if(p==0 && q==0){p=c[u];q=Max1+Max2+1;}
    else if(c[u]*q<(Max1+Max2+1)*p){p=c[u];q=Max1+Max2+1;}
    for(int v:edge[u]){
        if(v==par) continue;
        if(c[u]!=1) redfs(v,u,0);
        else redfs(v,u,max(len,(dep[v]==Max1?Max2:Max1))+1);
    }
}
void solve(){
    cin >> n;
    for(int i=1;i<n;i++){
        int u,v;cin >> u >> v;
        edge[u].push_back(v);
        edge[v].push_back(u);
    }
    for(int i=1;i<=n;i++) cin >> c[i];
    dfs(1,0);redfs(1,0,0);
    if(ans!=0 && q<p*ans){p=1;q=ans;}
    int g=__gcd(p,q);p/=g;q/=g;
    cout << p << '/' << q << '\n';
}
signed main(){
    //freopen("TREE.INP","r",stdin);
    //freopen("TREE.OUT","w",stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    int test=1;//cin >> test;
    while(test--) 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