Submission #726407

#	Time	Username	Problem	Language	Result	Execution time	Memory
726407		YugiHacker	Mag (COCI16_mag)	C++17	120 / 120	593 ms	180348 KiB

mag

/*
	www.youtube.com/YugiHackerChannel
	oj.vnoi.info/user/YugiHackerKhongCopCode
*/
#include<bits/stdc++.h>
#define el cout<<"\n"
#define f0(i,n) for(int i=0;i<n;++i)
#define f1(i,n) for(int i=1;i<=n;++i)
#define maxn 1000006
using namespace std;
struct frac
{
    long long x, y;
    frac(){}
    frac(long long x, long long y): x(x), y(y){}
    friend bool operator < (frac a, frac b)
    {
        return a.x * b.y < a.y * b.x;
    }
    void output()
    {
        long long g = __gcd(x, y);
        cout << x/g << '/' << y/g;
    }
}ans(1e9, 1);
int n;
vector <int> a[maxn];
int c[maxn];
int down[2][maxn], up[maxn];
void dfs(int u, int p)
{
    for (int v:a[u]) if (v != p)
    {
        dfs(v, u);
        if (c[v] == 1)
        {
            if (down[0][u] < down[0][v] + 1)
                down[1][u] = down[0][u], down[0][u] = down[0][v] + 1;
            else if (down[1][u] < down[0][v] + 1)
                down[1][u] = down[0][v] + 1;
        }

    }
}
void dfs$(int u, int p)
{
    for (int v:a[u]) if (v != p)
    {
        if (c[u] == 1)
        {
            up[v] = up[u] + 1;
            if (c[v] == 1)
            {
                if (down[0][v] + 1 == down[0][u]) up[v] = max(up[v], down[1][u] + 1);
            }
            else up[v] = max(up[v], down[0][u] + 1);
        }
        dfs$(v, u);
    }
    vector <int> tmp;
    tmp.push_back(up[u]);
    tmp.push_back(down[0][u]);
    tmp.push_back(down[1][u]);
    sort(tmp.begin(), tmp.end(), greater<int>());
    ans = min(ans, frac(c[u], tmp[0] + tmp[1] + 1));
}
main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n;
    f1 (i, n-1)
    {
        int u, v; cin >> u >> v;
        a[u].push_back(v);
        a[v].push_back(u);
    }
    f1 (i, n) cin >> c[i];
    dfs(1, 0);
    dfs$(1, 0);
    ans.output();
}

Compilation message (stderr)

mag.cpp:67:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   67 | main()
      | ^~~~

• 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