HDU 1561 The more, The Better(树形DP）

题目链接

和Vijos上的选课一模一样。。无奈效率700+，怎么这么慢啊。。。

 1 #include <stdio.h>

 2 #include <string.h>

 3 #include <stdlib.h>

 4 struct node

 5 {

 6     int left,right;

 7 }tree[301];

 8 int p[301],dp[301][301];

 9 int max(int a,int b)

10 {

11     return a > b? a:b;

12 }

13 void insert(int son,int father)

14 {

15     int t;

16     if(!tree[father].left)

17     {

18        tree[father].left = son;

19     }

20     else

21     {

22         t = tree[father].left;

23         while(tree[t].right)

24         {

25             t = tree[t].right;

26         }

27         tree[t].right = son;

28     }

29 }

30 int dfs(int x,int y)

31 {

32     int i;

33     if(dp[x][y] > 0)

34     return dp[x][y];

35     if(x == 0||y == 0)

36     return 0;

37     dp[x][y] = dfs(tree[x].right,y);

38     for(i = 0;i <= y-1;i ++)

39     {

40         dp[x][y] = max(dp[x][y],dfs(tree[x].left,i)+dfs(tree[x].right,y-1-i)+p[x]);

41     }

42     return dp[x][y];

43 }

44 int main()

45 {

46     int n,m,i,a;

47     while(scanf("%d%d",&n,&m)!=EOF)

48     {

49         if(!n&&!m) break;

50         memset(tree,0,sizeof(tree));

51         memset(dp,0,sizeof(dp));

52         for(i = 1;i <= n;i ++)

53         {

54             scanf("%d%d",&a,&p[i]);

55             insert(i,a);

56         }

57         printf("%d\n",dfs(tree[0].left,m));

58     }

59     return 0;

60 }