Submission #210413

#	Time	Username	Problem	Language	Result	Execution time	Memory
210413		DrumpfTheGodEmperor	Mergers (JOI19_mergers)	C++14	0 / 100	96 ms	56432 KiB

mergers

#include <bits/stdc++.h>
#define bp __builtin_popcountll
#define pb push_back
#define in(s) freopen(s, "r", stdin);
#define out(s) freopen(s, "w", stdout);
#define inout(s, end1, end2) freopen((string(s) + "." + end1).c_str(), "r", stdin),\
		freopen((string(s) + "." + end2).c_str(), "w", stdout);
#define fi first
#define se second
#define bw(i, r, l) for (int i = r - 1; i >= l; i--)
#define fw(i, l, r) for (int i = l; i < r; i++)
#define fa(i, x) for (auto i: x)
using namespace std;
const int mod = 1e9 + 7, inf = 1061109567;
const long long infll = 4557430888798830399;
const int N = 5e5 + 5;
int n, k, a[N], dep[N], par[N][20], alllca[N];
vector<int> g[N];
void dfs(int u, int p) {
	par[u][0] = p;
	fa (v, g[u]) if (v != p) {
		dep[v] = dep[u] + 1;
		dfs(v, u);
	}
}
void sparse() {
	fw (j, 1, 20) fw (i, 0, n) if (par[i][j - 1] != -1) {
		par[i][j] = par[par[i][j - 1]][j - 1];
	}
}
int getLCA(int u, int v) {
	if (u == -1) return v;
	if (v == -1) return u;
	if (dep[u] < dep[v]) swap(u, v);
	int diff = dep[u] - dep[v];
	fw (i, 0, 20) if (diff & (1 << i)) u = par[u][i];
	if (u == v) return u;
	bw (i, 20, 0) if (par[u][i] != par[v][i]) {
		u = par[u][i], v = par[v][i];
	}
	return par[u][0];
}
bool col[N];
int mnDep[N];
void dfs2(int u, int p) {
	mnDep[u] = dep[alllca[a[u]]];
	fa (v, g[u]) if (v != p) {
		dfs2(v, u);
		mnDep[u] = min(mnDep[u], mnDep[v]);
	}
	if (mnDep[u] == dep[u]) col[u] = 0;
	else col[u] = 1;
}
signed main() {
	#ifdef BLU
	in("blu.inp");
	#endif
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	cin >> n >> k;
	fw (i, 1, n) {
		int u, v;
		cin >> u >> v;
		u--, v--;
		g[u].pb(v), g[v].pb(u);
	}
	fw (i, 0, n) cin >> a[i], a[i]--;
	//Find all subtrees that can be splitted. Color them white, everything else black. 
	memset(par, -1, sizeof par);
	dep[0] = 0;
	dfs(0, -1);
	sparse();
	fw (i, 0, k) alllca[i] = -1;
	fw (i, 0, n) alllca[a[i]] = getLCA(alllca[a[i]], i);
	dfs2(0, -1);
	int cnt = 0;
	fw (i, 0, n) if (col[i] == 0) cnt++;
	cout << cnt / 2;
	return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30