//继续水一道树形dp
1 #include "iostream" 2 #include "cstdio" 3 #include "cstring" 4 #include "algorithm" 5 #include "cmath" 6 using namespace std; 7 __int64 dp[100010][2]; 8 bool vis[100010]; 9 int tot, first[100010 << 1], next[100010 << 1], to[100010 << 1]; 10 int n, ans[100010]; 11 void dfs(int root) 12 { 13 vis[root] = 1; 14 int edge, son; 15 for(edge = first[root]; edge; edge = next[edge]) { 16 son = to[edge]; 17 if(!vis[son]) { 18 dfs(son); 19 dp[root][0] = max(dp[root][0], dp[son][0]); 20 dp[root][1] = max(dp[root][1], dp[son][1]); 21 } 22 } 23 __int64 rem = ans[root] + dp[root][0] - dp[root][1]; 24 if(rem < 0) 25 dp[root][0] -= rem; 26 else 27 dp[root][1] += rem; 28 } 29 30 int main() 31 { 32 int i; 33 scanf("%d", &n); 34 int a, b; 35 for(i = 1; i <= n - 1; ++i) { 36 scanf("%d%d", &a, &b); 37 next[++tot] = first[a]; 38 first[a] = tot; 39 to[tot] = b; 40 next[++tot] = first[b]; 41 first[b] = tot; 42 to[tot] = a; 43 } 44 for(i = 1; i <= n; ++i) { 45 scanf("%d", &ans[i]); 46 } 47 dfs(1); 48 printf("%I64d ", dp[1][0] + dp[1][1]); 49 }