Submission #707152

#	Time	Username	Problem	Language	Result	Execution time	Memory
707152		YugiHacker	Mag (COCI16_mag)	C++14	72 / 120	483 ms	201612 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 h[maxn], d[maxn]; ///h : update from v to u, d : update from par to u
int ma[2][maxn];
void dfs(int u, int p)
{
    d[u] = h[u] = (c[u] == 1);
    for (int v:a[u]) if (v != p)
    {
        d[v] = (c[v] == 1) ? d[u] + 1 : 0;
        dfs(v, u);
        if (h[v] > ma[0][u]) ma[1][u] = ma[0][u], ma[0][u] = h[v];
        else if (h[v] > ma[1][u]) ma[1][u] = h[v];
        if (c[u] == 1) h[u] = max(h[u], (c[v] == 1) ? h[v] + 1 : 0);
    }
}
void redfs(int u, int p)
{
    for (int v:a[u]) if (v != p) redfs(v, u);

    vector <int> tmp;
    tmp.push_back(ma[0][u]);
    tmp.push_back(ma[1][u]);
    int maxP = d[p];
    if (c[p] == 1)
    {
        if (h[u] == ma[0][p]) maxP = max(maxP, ma[1][p] + 1);
        else maxP = max(maxP, ma[0][p] + 1);
    }
    tmp.push_back(maxP);
    sort(tmp.begin(), tmp.end());
    frac cur(c[u], tmp[1] + tmp[2] + 1);
    if (cur < ans) ans = cur;
}
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);
    redfs(1, 0);
    ans.output();
}

Compilation message (stderr)

mag.cpp:61:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   61 | main()
      | ^~~~

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