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;
}

原文地址：https://www.cnblogs.com/lylyl/p/11681661.html