제출 #98271

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
98271		dalgerok	Mag (COCI16_mag)	C++17	24 / 120	604 ms	138544 KiB

mag

#include<bits/stdc++.h>
using namespace std;



const int N = 1e6 + 5;



int n, a[N], dp[N], ans1 = -1, ans2 = -1;
vector < int > g[N];


void dfs1(int v, int pr = -1){
    int mx1 = 0, mx2 = 0;
    for(int to : g[v]){
        if(to != pr){
            dfs1(to, v);
            if(dp[to] > mx1){
                mx2 = mx1;
                mx1 = dp[to];
            }
            else if(dp[to] > mx2){
                mx2 = dp[to];
            }
        }
    }
    if(a[v] == 1){
        dp[v] = mx1 + 1;
        ans1 = max(ans1, mx1 + mx2 + 1);
    }
}
void dfs2(int v, int pr = -1){
    int mx1 = 0, mx2 = 0;
    for(int to : g[v]){
        if(to != pr){
            dfs2(to, v);
            if(dp[to] > mx1){
                mx2 = mx1;
                mx1 = dp[to];
            }
            else if(dp[to] > mx2){
                mx2 = dp[to];
            }
        }
    }
    if(a[v] == 2){
        dp[v] = mx1 + 1;
        ans2 = max(ans2, mx1 + mx2 + 1);
    }
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n;
    for(int i = 1; i < n; i++){
        int x, y;
        cin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    ans1 = ans2 = -1;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        if(a[i] == 1){
            ans1 = 1;
        }
        if(a[i] == 2){
            ans2 = 1;
        }
    }
    memset(dp, 0, sizeof(dp));
    dfs1(1);
    memset(dp, 0, sizeof(dp));
    dfs2(1);
    if(ans1 != -1){
        if(ans2 == -1){
            cout << "1/" << ans1;
        }
        else if(ans1 * 2 > ans2){
            cout << "1/" << ans1;
        }
        else{
            if(ans2 & 1){
                cout << "2/" << ans2;
            }
            else{
                cout << "1/" << ans2 / 2;
            }
        }
        return 0;
    }
    int ans = 2e9;
    for(int i = 1; i <= n; i++){
        ans = min(ans, a[i]);
    }
    cout << ans << "/1";
}

• Subtask 1: 12 / 12
• Subtask 2: 0 / 12
• Subtask 3: 0 / 12
• Subtask 4: 0 / 12
• Subtask 5: 0 / 12
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• Subtask 10: 12 / 12