hdu4632 Palindrome subsequence ——区间动态规划

link:http://acm.hdu.edu.cn/showproblem.php?pid=4632

refer to:

o(╯□╰)o……明明百度找的题解，然后后来就找不到我看的那份了，这位哥们对不住了……

 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <cmath>
 #include <cctype>
 #include <algorithm>
 #include <queue>
 #include <deque>
 #include <queue>
 #include <list>
 #include <map>
 #include <set>
 #include <vector>
 #include <utility>
 #include <functional>
 #include <fstream>
 #include <iomanip>
 #include <sstream>
 #include <numeric>
 #include <cassert>
 #include <ctime>
 #include <iterator>
 const int INF = 0x3f3f3f3f;
 const int dir[][] = {{-,},{,},{,-},{,},{-,-},{-,},{,-},{,}};
 using namespace std;
 char a[];
 int dp[][];
 const int MOD = ;
 int main(void)
 {
     #ifndef ONLINE_JUDGE
     freopen("in.txt", "r", stdin);
     #endif // ONLINE_JUDGE
     ios::sync_with_stdio(false);
     int t; cin>>t;
     for (int k = ; k <= t; ++k)
     {
         cin>>a; int len = strlen(a);
         memset(dp, , sizeof(dp));
         for (int i = ; i < len; ++i) for (int j = ; j < len; ++j)
             if (i==j) dp[i][j] = ;
         for (int i = ; i < len; ++i)
         {
             for (int j = ; i+j < len; ++j)
             {
                 if (a[i+j] == a[j])
                 {
                     dp[j][i+j] = dp[j][i+j-] + dp[j+][i+j] + ;
                 }
                 else
                 {
                     dp[j][i+j] = dp[j+][i+j] + dp[j][i+j-] - dp[j+][i+j-];
                 }
                 dp[j][i+j] = (dp[j][i+j] + MOD)%MOD;
             }
         }
         cout<< "Case "<<k<< ": "<<dp[][len-]<<endl;
     }
     return ;
 }
 /*
     模拟一下第二个样例 aaaaa 就懂了
 */

o(╯□╰)o
永远感觉规划是一个很神奇的东西，比如这道。想明白了就感觉很神奇~