hiho 1055 刷油漆树形dp

一个简单的树上的背包问题。
代码：
 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <cmath>
 6 #include <algorithm>
 7 #include <string>
 8 #include <queue>
 9 #include <stack>
10 #include <vector>
11 #include <map>
12 #include <set>
13 #include <functional>
14 #include <cctype>
15 #include <time.h>
16 
17 using namespace std;
18 
19 const int INF = 1<<30;
20 
21 struct Graph {
22     static const int MAXN = 111;
23     static const int MAXM = MAXN*2;
24 
25     int head[MAXN];
26     int next[MAXM], to[MAXM], use;
27 
28     int val[MAXN], size[MAXN];
29     int m;
30 
31     void init(int n, int m) {
32         memset(head, -1, sizeof(head));
33         use = 0;
34 
35         this->m = m;
36         for (int i = 1; i <= n; i++) scanf("%d", &val[i]);
37         int u, v;
38         for (int i = 1; i < n; i++) {
39             scanf("%d%d", &u, &v);
40             addEdge(u, v);
41             addEdge(v, u);
42         }
43     }
44 
45     inline void addEdge(int u, int v) {
46         next[use] = head[u];
47         to[use] = v;
48         head[u] = use++;
49     }
50 
51     int dp[MAXN][MAXN];
52 
53     void dfs(int u, int pre) {
54         memset(dp[u], 0, sizeof(dp[u]));
55         size[u] = 1;
56         for (int p = head[u]; p != -1; p = next[p]) {
57             int v = to[p];
58             if (v==pre) continue;
59             dfs(v, u);
60             size[u] += size[v];
61         }
62         dp[u][1] = val[u];
63         for (int p = head[u]; p != -1; p = next[p]) {
64             int v = to[p];
65             if (v==pre) continue;
66             for (int i = size[u]; i > 0; i--)
67                 for (int j = 1; j <= size[v]; j++) {
68                     if (i+j>size[u]) break;
69                     dp[u][i+j] = max(dp[u][i+j], dp[u][i]+dp[v][j]);
70                 }
71         }
72     }
73 
74     void solve() {
75         int ans = 0;
76         dfs(1, 1);
77         for (int i = 1; i <= m; i++)
78             ans = max(ans, dp[1][i]);
79         printf("%d
", ans);
80     }
81 }solver;
82 
83 int main() {
84     #ifdef Phantom01
85         freopen("1055.txt", "r", stdin);
86     #endif //Phantom01
87 
88     int n, m;
89     while (scanf("%d%d", &n, &m)!=EOF) {
90         solver.init(n, m);
91         solver.solve();
92     }
93 
94     return 0;
95 }
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hiho 1055 刷油漆 树形dp

hiho 1055 刷油漆树形dp
