Submission #720608

#	Time	Username	Problem	Language	Result	Execution time	Memory
720608		Ahmed57	Mag (COCI16_mag)	C++14	0 / 120	4069 ms	262144 KiB

mag

#include <bits/stdc++.h>

using namespace std;
vector<int> adj[1000006];
int ma[1000006];
int lon[1000006];
int pref[1000006];
int suf[1000006];vector<int> ch;
int n ;
void calc(int i,int pr){
    int ch = (ma[i]==1?1:0);
    for(auto j:adj[i]){
        if(j!=pr){
            calc(j,i);
            if(ma[i]==1)ch = max(ch,lon[j]+1);
        }
    }
    lon[i] = ch;
}
int maa = 0;
void dfs(int i,int pr){
    maa = max(maa,lon[i]);
    for(auto j:adj[i]){
        if(j==pr)continue;
        dfs(j,i);
    }
    if(ma[i]==1){
        int firstma = 0 , secondma = 0;
        for(auto j:adj[i]){
            if(j==pr)continue;
            if(firstma<=lon[j]){
                secondma = firstma;
                firstma = lon[j];
            }else if(secondma<=lon[j]){
                secondma = lon[j];
            }
        }
        maa = max(maa,firstma+secondma+1);
    }
}
bool ss = 0;int mm = 0;
void reroor(int i,int pr,int cnt){
    if(ma[i]==2){
        int firstma = cnt , secondma = 0;
        for(auto j:adj[i]){
            if(j==pr)continue;
            if(firstma<=lon[j]){
                secondma = firstma;
                firstma = lon[j];
            }else if(secondma<=lon[j]){
                secondma = lon[j];
            }
        }
        if(firstma==secondma&&firstma==maa){
            ss = 1;
        }
    }
    ch.clear();
    mm = 0;
    for(auto j:adj[i]){
        if(j==pr)continue;
        pref[j] = mm;
        mm = max(mm,lon[j]);
        ch.push_back(j);
    }
    mm = cnt;
    reverse(ch.begin(),ch.end());
    for(auto j:ch){
        suf[j] = mm;
        mm = max(mm,lon[j]);
    }
    for(auto j:adj[i]){
        reroor(j,i,(ma[i]==1?max(suf[j],pref[j])+1:0));
    }
}
signed main(){
    cin>>n;
    for(int i = 0;i<n-1;i++){
        int a,b;cin>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    int mi = 1e9;
    for(int i = 0;i<n;i++){
        cin>>ma[i+1];
        mi = min(mi,ma[i+1]);
    }
    if(mi!=1){
        cout<<mi<<"/"<<1<<endl;
        return 0;
    }
    calc(1,0);
    dfs(1,0);
    reroor(1,0,0);
    if(ss) cout<<2<<"/"<<2*maa+1<<endl;
    else cout<<1<<"/"<<maa<<endl;
}

• Subtask 1: 0 / 12
• Subtask 2: 0 / 12
• Subtask 3: 0 / 12
• Subtask 4: 0 / 12
• Subtask 5: 0 / 12
• Subtask 6: 0 / 12
• Subtask 7: 0 / 12
• Subtask 8: 0 / 12
• Subtask 9: 0 / 12
• Subtask 10: 0 / 12