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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