51nodP1378夹克老爷的愤怒

将每一个点按照深度排序,每次取出深度最大的点,向上跳k个后再扩展标记.

#include<bits/stdc++.h>
#define il inline
#define rg register
#define gi read<int>
using namespace std;
const int O = 1e5 + 10;
struct Edge { int to, nt; } e[O << 1];
template<class TT>
il TT read() {
	TT o = 0,fl = 1; char ch = getchar();
	while (!isdigit(ch) && ch != '-') ch = getchar();
	if (ch == '-') fl = -1, ch = getchar();
	while (isdigit(ch)) o = o * 10 + ch - '0', ch = getchar();
	return fl * o;
}
bool vis[O];
int n, k, cnt, mx, ans, head[O], f[O];
vector<int>G[O];
il void add(int u, int v) {
	e[++cnt] = (Edge){v, head[u]};
	head[u] = cnt;
}
il void dfs_dep(int u, int fa, int dep) {
	f[u] = fa;
	++dep;
	G[dep].push_back(u);
	if (mx < dep) mx = dep;
	for (int i = head[u]; ~i; i = e[i].nt) {
		int v = e[i].to;
		if (v == fa) continue;
		dfs_dep(v, u, dep);
	}
}
il void dfs_mark(int u, int fa, int K) {
	vis[u] = 1;
	if (K++ == k) return;
	for (int i = head[u]; ~i; i = e[i].nt)
		if (e[i].to ^ fa) dfs_mark(e[i].to, u, K);
}
int main() {
	memset(head, -1, sizeof head);
	n = gi(), k = gi();
	for (int i = 1; i < n; ++i) {
		int u = gi(), v = gi();
		add(u, v); add(v, u);
	}
	G[0].push_back(0);
	dfs_dep(0, -1, 0);
	for(int i = mx; i; --i) {
		for (unsigned int j = 0; j < G[i].size(); ++j) {
			int v = G[i][j];
			if (vis[v]) continue;
			for (int i = 1; i <= k; ++i)
				if (f[v] != -1) v = f[v];
				else break;
			dfs_mark(v, -1, 0);
			ans++;
		}
	}
	printf("%d\n", ans);
	return 0;
}