POJ 2955 Brackets(区间DP)

题目链接

 1 #include <iostream>

 2 #include <cstdio>

 3 #include <cstring>

 4 #include <vector>

 5 #include <cmath>

 6 #include <algorithm>

 7 using namespace std;

 8 int dp[101][101];

 9 char str[101];

10 int judge(int x,int y)

11 {

12     if(str[x] == '['&&str[y] == ']')

13     return 1;

14     else if(str[x] == '('&&str[y] == ')')

15     return 1;

16     return 0;

17 }

18 int dfs(int L,int R)

19 {

20     int maxz,i;

21     maxz = 0;

22     if(dp[L][R] != -1)

23     return dp[L][R];

24     if(L >= R)

25     return 0;

26     if(judge(L,R))

27     maxz = max(maxz,2 + dfs(L+1,R-1));

28     for(i = L;i < R;i ++)

29     maxz = max(maxz,dfs(L,i)+dfs(i+1,R));

30     return dp[L][R] = maxz;

31 }

32 int main()

33 {

34     int len;

35     while(scanf("%s",str)!=EOF)

36     {

37         if(strcmp(str,"end") == 0)

38         break;

39         memset(dp,-1,sizeof(dp));

40         len = strlen(str);

41         printf("%d\n",dfs(0,len-1));

42     }

43     return 0;

44 }