第二道树形DP，先是MLE。后来仅需改小邻接矩阵的第二个维度到30就过了。
1 #include <cstdio> 2 #include <cstring> 3 #include <cstdlib> 4 5 #define MAXN 6005 6 7 int rat[MAXN]; 8 int dp[MAXN][2]; 9 int adj[MAXN][30]; 10 bool visit[MAXN]; 11 int n; 12 13 int max(int a, int b) { 14 return a>b ? a:b; 15 } 16 17 void dfs(int r) { 18 int i, v; 19 20 visit[r] = true; 21 dp[r][1] = rat[r]; 22 for (i=1; i<=adj[r][0]; ++i) { 23 v = adj[r][i]; 24 if (visit[v]) 25 continue; 26 dfs(v); 27 // r node not attend, v get the maximum 28 dp[r][0] += max(dp[v][0], dp[v][1]); 29 // r node attend, v not attend. 30 dp[r][1] += dp[v][0]; 31 } 32 } 33 34 int main() { 35 int i, j, k; 36 int a, b; 37 38 #ifndef ONLINE_JUDGE 39 freopen("data.in", "r", stdin); 40 #endif 41 42 while (scanf("%d", &n) != EOF) { 43 for (i=1; i<=n; ++i) 44 scanf("%d", &rat[i]); 45 46 memset(adj, 0, sizeof(adj)); 47 memset(visit, false, sizeof(visit)); 48 memset(dp, 0, sizeof(dp)); 49 while (scanf("%d %d", &a, &b)!=EOF && (a||b)) { 50 ++adj[a][0]; 51 adj[a][adj[a][0]] = b; 52 ++adj[b][0]; 53 adj[b][adj[b][0]] = a; 54 } 55 56 dfs(1); 57 printf("%d ", max(dp[1][0], dp[1][1])); 58 } 59 60 return 0; 61 }