CF - Ostap & Tree

Solution described by editorial is terrible, but we can do better! This runs in $O(NK)$ time. (proof?)

vmi yes[MX], no[MX];
vi adj[MX];
int n,k;

void dfs(int x, int y) {
    yes[x] = no[x] = {1}; // black, not black
    // dist of closest good vertex
    // or dist of farthest bad vertex
    auto ad = [](vmi& a, int b, mi c) {
        while (sz(a) <= b) a.pb(0);