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 }
