2015 Multi-University Training Contest 3 hdu 5326 Work

Work

#include <bits/stdc++.h>
using namespace std;
const int maxn = 100010;
struct arc {
int to,next;
arc(int x = 0,int y = -1) {
to = x;
next = y;
}
} e[maxn];
int head[maxn],tot;
void add(int u,int v) {
e[tot] = arc(v,head[u]);
head[u] = tot++;
e[tot] = arc(u,head[v]);
head[v] = tot++;
}
int ind[maxn],cnt[maxn],ret,n,k;
void dfs(int u,int fa) {
cnt[u] = 1;
for(int i = head[u]; ~i; i = e[i].next) {
if(e[i].to == fa) continue;
dfs(e[i].to,u);
cnt[u] += cnt[e[i].to];
}
if(k + 1 == cnt[u]) ++ret;
}
int main() {
int u,v;
while(~scanf("%d%d",&n,&k)) {
memset(head,-1,sizeof head);
memset(ind,0,sizeof ind);
ret = tot = 0;
for(int i = 1; i < n; ++i) {
scanf("%d%d",&u,&v);
add(u,v);
++ind[v];
}
for(int i = 1; i <= n; ++i)
if(!ind[i]) {
dfs(i,-1);
break;
}
printf("%d\n",ret);
}
return 0;
}