P3047 [USACO12FEB]附近的牛Nearby Cows

https://www.luogu.org/problemnew/show/P304 1 #include <bits/stdc++.h> 2 #define up(i,l,r) for(register int i = (l); i <= (r); ++i) 3 #define dn(i,l,r) for(register int i = (l); i >= (r); --i) 4 #define ll long long

 5 #define re register
 6 using namespace std;
 7 
 8 template <typename T> void in(T &x) {
 9     x = 0; T f = 1; char ch = getchar();
10     while(!isdigit(ch)) {if(ch == '-') f = -1; ch = getchar();}
11     while( isdigit(ch)) {x = 10 * x + ch - 48; ch = getchar();}
12     x *= f;
13 }
14 
15 template <typename T> void out(T x) {
16     if(x < 0) x = -x , putchar('-');
17     if(x > 9) out(x/10);
18     putchar(x%10 + 48);
19 }
20 
21 int n,k;
22 const int N = 100007;
23 struct edge {
24     int v,nxt;
25 }e[N<<1]; int tot,head[N];
26 void add(int u,int v) {e[++tot] = (edge){v,head[u]}; head[u] = tot;}
27 
28 int f[2][N][25],c[N];
29 
30 void dfs1(int u,int fa) {
31     up(i,0,k)
32     f[0][u][i] = c[u];

33     for(re int i = head[u]; i ; i = e[i].nxt) {
34         int v = e[i].v;
35         if(v == fa) continue;
36         dfs1(v,u);
37         up(i,1,k)
38         f[0][u][i] += f[0][v][i-1];
39     }
40 }
41 
42 void dfs2(int u,int fa) {
43     
44     f[1][u][0] = c[u];
45     up(i,1,k) f[1][u][i] = f[1][fa][i-1] - f[0][u][i-2] + f[0][u][i];
46     //别忘了+f[0][u][i] 
47     for(re int i = head[u]; i ; i = e[i].nxt) {
48         int v = e[i].v;
49         if(v == fa) continue;
50         dfs2(v,u);
51     }
52 }
53 
54 int main() {
55     freopen("input.txt","r",stdin);
56     in(n); in(k);
57     int u,v;
58     up(i,1,n-1) {
59         in(u); in(v);
60         add(u,v); add(v,u);
61     }
62     up(i,1,n) in(c[i]);
63     dfs1(1,0);
64     
65     up(i,1,k)
66     f[1][0][i] = f[0][1][i-1];
67     //必须给0号节点赋初值 
68     dfs2(1,0);
69     
70     up(i,1,n) out(f[1][i][k]),putchar('\n');
71     return 0;
72 }

 

posted @ 2019-03-21 10:56  陈星卿  阅读(82)  评论(0)  编辑  收藏  举报