E. Gardener and Tree

Problem - E - Codeforces (Unofficial mirror site, accelerated for Chinese users)

遍历求每个点的深度， 最后面和K比较就行。

/*//
Problem: E. Gardener and Tree
Contest: CF748
URL: https://codeforces.ml/contest/1593/problem/E
/*/
#include <bits/stdc++.h>
#define ll long long int
#define ull unsigned long long int
using namespace std;
const int inf = 0x3f3f3f3f;
const ll ll_inf = 0x3f3f3f3f3f3f3f3f;
const ll mod = 1e9 + 7;
const int maxn = 1e5 + 5;

int main(int argc, char const *argv[]) {
	ios::sync_with_stdio(false);
	cin.tie(0);     cout.tie(0);
	int T;
	cin >> T;
	while (T --) {
		int n, k;
		cin >> n >> k;
		vector<int > g[n + 1];
		vector<int > num(n + 1);
		vector<int > bian(n + 1);
		for (int i = 1; i < n; i ++) {
			int x, y;
			cin >> x >> y;
			x--, y --;
			g[x].push_back(y);
			g[y].push_back(x);
			bian[x] ++;
			bian[y] ++;
		}
		queue<int > q;
		for (int i = 0; i < n; i ++) {
			if (g[i].size() == 1) {
				q.push(i);
				num[i] = 1;
			}

		}
		while (!q.empty()) {
			int tmp = q.front();
			q.pop();
			for (auto x : g[tmp]) {
				bian[x] --;
				if (bian[x] == 1) {
					q.push(x);
					num[x] = num[tmp] + 1;
				}
			}
		}
		int ans = 0
		for (auto &x : num) {
			if (x > k) {
				ans ++;
			}
		}
		cout << ans << endl;
	}
	return 0;
}