제출 #98341

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
98341		dalgerok	Mag (COCI16_mag)	C++17	12 / 120	791 ms	215088 KiB

mag

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


const int N = 1e6 + 5;


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

inline void upd(int &x, int y){
    if(x < y){
        x = y;
    }
}

void dfs1(int v, int pr = -1){
    for(int to : g[v]){
        if(to != pr){
            dfs1(to, v);
            upd(dp_down[v], dp_down[to]);
        }
    }
    if(a[v] != 1){
        dp_down[v] = 0;
    }
}

void dfs2(int v, int pr = -1){
    if(pr != -1){
        g[v].erase(find(g[v].begin(), g[v].end(), pr));
    }
    int sz = (int)g[v].size();
    vector < int > pref(sz + 2), suf(sz + 2);
    for(int i = 1; i <= sz; i++){
        pref[i] = max(pref[i - 1], dp_down[g[v][i - 1]] + (a[g[v][i - 1]] == 1));
    }
    for(int i = sz; i >= 1; i--){
        suf[i] = max(suf[i + 1], dp_down[g[v][i - 1]] + (a[g[v][i - 1]] == 1));
    }
    for(int i = 1; i <= sz; i++){
        int to = g[v][i - 1];
        if(a[v] == 1){
            dp_up[to] = max({pref[i - 1], suf[i + 1], dp_up[v]}) + 1;
        }
        else{
            dp_up[to] = 0;
        }
        dfs2(to, v);
    }
}

inline void check(int x, int y){
    /// x / y < ans1 / ans2;
    /// x * ans2 < ans1 * y;
    if(ans1 == -1){
        ans1 = x;
        ans2 = y;
    }
    else if(1LL * x * ans2 < 1LL * ans1 * y){
        ans1 = x;
        ans2 = y;
    }
}

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);
    }
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    dfs1(1);
    dfs2(1);
    for(int i = 1; i <= n; i++){
        int x = a[i], y = 1 + dp_up[i] + dp_down[i];
        check(x, y);
    }
    int g = __gcd(ans1, ans2);
    cout << ans1 << "/" << ans2;
}

컴파일 시 표준 에러 (stderr) 메시지

mag.cpp: In function 'int main()':
mag.cpp:85:9: warning: unused variable 'g' [-Wunused-variable]
     int g = __gcd(ans1, ans2);
         ^

• Subtask 1: 12 / 12
• Subtask 2: 0 / 12
• Subtask 3: 0 / 12
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