【HDOJ】1520 Anniversary party

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。

 #include <cstdio>
 #include <cstring>
 #include <cstdlib>

 #define MAXN 6005

 int rat[MAXN];
 int dp[MAXN][];
 int adj[MAXN][];
 bool visit[MAXN];
 int n;

 int max(int a, int b) {
     return a>b ? a:b;
 }

 void dfs(int r) {
     int i, v;

     visit[r] = true;
     dp[r][] = rat[r];
     for (i=; i<=adj[r][]; ++i) {
         v = adj[r][i];
         if (visit[v])
             continue;
         dfs(v);
         // r node not attend, v get the maximum
         dp[r][] += max(dp[v][], dp[v][]);
         // r node attend, v not attend.
         dp[r][] += dp[v][];
     }
 }

 int main() {
     int i, j, k;
     int a, b;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
     #endif

     while (scanf("%d", &n) != EOF) {
         for (i=; i<=n; ++i)
             scanf("%d", &rat[i]);

         memset(adj, , sizeof(adj));
         memset(visit, false, sizeof(visit));
         memset(dp, , sizeof(dp));
         while (scanf("%d %d", &a, &b)!=EOF && (a||b)) {
             ++adj[a][];
             adj[a][adj[a][]] = b;
             ++adj[b][];
             adj[b][adj[b][]] = a;
         }

         dfs();
         printf("%d\n", max(dp[][], dp[][]));
     }

     return ;
 }