loj 1025(记忆化搜索）

题目链接：http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=25902

 1 #include<iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<algorithm>

 5 using namespace std;

 6 typedef long long ll;

 7 #define FILL(a,b) memset(a,b,sizeof(a))

 8 

 9 ll dp[77][77];

10 int n;

11 char str[77];

12 

13 ll dfs(int l,int r)

14 {

15     if(dp[l][r]!=-1)return dp[l][r];

16     if(l>r)return dp[l][r]=0;

17     if(l==r)return dp[l][r]=1;

18     dp[l][r]=0;

19     if(str[l]==str[r])dp[l][r]+=dfs(l+1,r-1)+1;

20     dp[l][r]+=dfs(l+1,r)+dfs(l,r-1)-dfs(l+1,r-1);

21     return dp[l][r];

22 }

23 

24 

25 int main()

26 {

27     int _case,t=1;

28     scanf("%d",&_case);

29     while(_case--){

30         scanf("%s",str);

31         n=strlen(str);

32         FILL(dp,-1);

33         printf("Case %d: %lld\n",t++,dfs(0,n-1));

34     }

35     return 0;

36 }

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