51Nod 1092 回文字符串

最开始毫无头绪，然后参照了一位dalao的博客，思路是一个正序的字符串将其逆序，然后求最长公共子序列（LCS）,emm也属于动态规划。

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

 const int maxn = ;
 char s1[maxn];
 char s2[maxn];

 int dp[maxn][maxn];

 int main(){
     cin >> s1;
     int len = strlen(s1);
     for (int i = ,j = len - ; i < len; i++,j--){
         s2[i] = s1[j];
     }
     memset(dp, , sizeof(dp));
     for (int i = ; i <= len; i++){
         for (int j = ; j <= len; j++){
             if (s1[i - ] == s2[j - ]){
                 dp[i][j] = max(dp[i - ][j - ] + , max(dp[i - ][j], dp[i][j - ]));
             }
             else{
                 dp[i][j] = max(dp[i - ][j - ], max(dp[i - ][j], dp[i][j - ]));
             }
         }
     }
     cout << len - dp[len][len] << endl;
     return ;
 }