hdu1513 Palindrome

思路：

dp+滚动数组。

实现：

 #include <iostream>
 #include <cstdio>
 #include <string>
 #include <algorithm>
 #include <cstring>
 using namespace std;

 int n;
 string str;
 int dp[][];

 int solve()
 {
     for (int i = n - ; i >= ; i--)
     {
         for (int j = i + ; j < n; j++)
         {
             if (str[i] == str[j])
             {
                 dp[i & ][j] = dp[(i + ) & ][j - ];
             }
             else
             {
                 dp[i & ][j] = min(dp[i & ][j - ], dp[(i + ) & ][j]) + ;
             }
         }
     }
     return dp[][n - ];
 }

 int solve2()
 {
     for (int j = ; j <= n; j++)
     {
         for (int i = ; i <= n - j; i++)
         {
             if (str[i] == str[i + j - ])
             {
                 dp[i][j % ] = dp[i + ][(j - ) % ];
             }
             else
             {
                 dp[i][j % ] = min(dp[i][(j - ) % ], dp[i + ][(j - ) % ]) + ;
             }
         }
     }
     return dp[][n % ];
 }
 int main()
 {
     while (cin >> n >> str)
     {
         memset(dp, , sizeof(dp));
         cout << solve2() << endl;
     }
     return ;
 }