区间DP UVA 10453 Make Palindrome

题目传送门

 /*
     题意：问最少插入多少个字符使得字符串变成回文串
     区间DP：dp[i][j]表示[l, r]的字符串要成为回文需要插入几个字符串，那么dp[l][r] = dp[l+1][r-1]; (str[l] == str[r])
             dp[l][r] = min (dp[l+1][r], dp[l][r-1]) + 1，然后按照状态转移递归输出路径
 */
 /************************************************
 * Author        :Running_Time
 * Created Time  :2015-8-17 14:42:57
 * File Name     :UVA_10453.cpp
  ************************************************/

 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 #define lson l, mid, rt << 1
 #define rson mid + 1, r, rt << 1 | 1
 typedef long long ll;
 const int MAXN = 1e3 + ;
 const int INF = 0x3f3f3f3f;
 const int MOD = 1e9 + ;
 char str[MAXN];
 int dp[MAXN][MAXN];

 void print(int l, int r)    {
     if (l > r)  return ;
     if (l == r) printf ("%c", str[l]);
     else if (str[l] == str[r])   {
         printf ("%c", str[l]);
         print (l + , r - );
         printf ("%c", str[l]);
     }
     else if (dp[l][r] == dp[l+][r] + )    {
         printf ("%c", str[l]);
         print (l + , r);
         printf ("%c", str[l]);
     }
     else    {
         printf ("%c", str[r]);
         print (l, r - );
         printf ("%c", str[r]);
     }
 }

 void work(void) {
     memset (dp, , sizeof (dp));
     int len = strlen (str);
     for (int i=; i<=len; ++i)  {
         for (int j=; j+i-<len; ++j)   {
             int k = j + i - ;
             int &res = dp[j][k] = INF;
             if (str[j] == str[k])   res = dp[j+][k-];
             res = min (res, min (dp[j+][k], dp[j][k-]) + );
         }
     }
     printf ("%d ", dp[][len-]);
     print (, len - ); puts ("");
 }

 int main(void)    {     //UVA 10453 Make Palindrome
     while (scanf ("%s", str) == )  {
         work ();
     }

     return ;
 }