Submission #679220

#	Time	Username	Problem	Language	Result	Execution time	Memory
679220		ziduo	Mag (COCI16_mag)	C++14	96 / 120	433 ms	223364 KiB

mag

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define f first
#define s second
int vals[1000000];
int dp[1000000][2];
vector<int> edges[1000000];
pair<int, int> answer;
void rec(int u, int p){
    for(int v: edges[u])if(v!=p)rec(v, u);
    if(vals[u]>2){
        dp[u][0] = 0;
        dp[u][1] = 0;
        return;
    }
    vector<int> use0;
    vector<int> use1;
    for(int v: edges[u])if(v!=p){
        use0.push_back(dp[v][0]);
        use1.push_back(dp[v][1]);
    }
    sort(use0.begin(), use0.end());
    sort(use1.begin(), use1.end());
    reverse(use0.begin(), use0.end());
    reverse(use1.begin(), use1.end());
    if(vals[u]==2){
        dp[u][0] = 0;
        if(use0.size()==0){
            dp[u][1] = 1;
            answer.s=max(answer.s, 1);
        }
        else{ 
            dp[u][1] = use0[0]+1;
            if(use0.size()==1)
                answer.s=max(answer.s,use0[0]+1);
            else
                answer.s=max(answer.s,use0[0]+1+use0[1]);
        }
    }
    else{
        if(use0.size()==0){
            dp[u][0] = 1;
            dp[u][1] = 0;
            answer.f=max(answer.f, 1);
        }
        else if(use0.size()==1){
            dp[u][0] = use0[0]+1;
            dp[u][1] = use1[0]+1;
            answer.f=max(answer.f, dp[u][0]);
            answer.s=max(answer.s, dp[u][1]);
        }
        else{
            dp[u][0] = use0[0]+1;
            dp[u][1] = use1[0]+1;
            answer.f=max(answer.f, use0[0]+use0[1]+1);
            answer.s=max(answer.s, use0[0]+use1[0]+1);
        }
    }
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int n;
    cin>>n;
    for(int i=0; i<n; i++)edges[i] = {};
    for(int i=0; i<n-1; i++){
        int u, v;cin>>u>>v;u--;v--;
        edges[u].push_back(v);
        edges[v].push_back(u);
    }
    answer.f=0; answer.s=0;
    for(int i=0; i<n; i++)cin>>vals[i];
    rec(0, -1);
    if(answer.f==0&&answer.s==0){
        int prin = vals[0];
        for(int i=1; i<n; i++)prin = min(prin, vals[i]);
        cout<<prin<<"/1\n";
    }
    else{
        if(answer.f>answer.s/2)
            cout<<"1/"<<answer.f<<'\n';
        else{
            if((answer.s%2)==0)cout<<"1/"<<(answer.s/2)<<'\n';
            else cout<<"2/"<<answer.s<<'\n';
        }
        
    }
    return 0;
}

• Subtask 1: 12 / 12
• Subtask 2: 0 / 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: 0 / 12