【HDOJ】1011 Starship Troopers

第一道树形DP。很容易理解。

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

 #define MAXN 105

 typedef struct {
     int n, p;
 } room_t;

 room_t rooms[MAXN];
 int adj[MAXN][MAXN];
 int dp[MAXN][MAXN];
 bool visit[MAXN];
 int n, m;

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

 void dfs(int r) {
     int i, j, k, num, v;

     visit[r] = true;
     num = (rooms[r].n+) / ;
     for (i=num; i<=m; ++i)
         dp[r][i] = rooms[r].p;

     for (i=; i<=adj[r][]; ++i) {
         v = adj[r][i];
         if (visit[v])
             continue;
         dfs(v);
         for (j=m; j>=num; --j) {
             for (k=; k+j<=m; ++k) {
                 if (dp[v][k]) {
                     dp[r][j+k] = max(dp[r][j+k], dp[r][j]+dp[v][k]);
                 }
             }
         }
     }
 }

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

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

     while (scanf("%d %d", &n, &m) != EOF) {
         if (n==- && m==-)
             break;
         memset(adj, , sizeof(adj));
         memset(visit, false, sizeof(visit));
         memset(dp, , sizeof(dp));
         for (i=; i<=n; ++i) {
             scanf("%d %d", &rooms[i].n, &rooms[i].p);
         }
         for (i=; i<n; ++i) {
             scanf("%d %d", &j, &k);
             ++adj[j][];
             ++adj[k][];
             adj[j][adj[j][]] = k;
             adj[k][adj[k][]] = j;
         }
         if (m == ) {
             printf("0\n");
             continue;
         }
         dfs();
         printf("%d\n", dp[][m]);
     }

     return ;
 }