字符串编辑距离

 
 
 
public class  {
   int dp[][];
 
 public int getStringSimilar(String s1, String s2) {
       int n, m;// respective length
      int i, j;// cursor
     n = s1.length();
     m = s2.length();
      if (n == 0 || m == 0) {
         return Math.abs(m - n);
         }
       
     dp = new int[n][m];
        for (i = 0; i < n; i++)
          dp[i][0] = 1 + i;
        for (i = 0; i < m; i++)
          dp[0][i] = 1 + i;
        for (i = 0; i < n; i++) 
         for (j = 0; j < m; j++) 
             if (s1.charAt(i) == s2.charAt(j))
                   dp[i][j] = getDP(i - 1, j - 1);
              else
                    //注意是min(a,b,c)三个形参
                 dp[i][j] = min(getDP(i - 1, j), getDP(i, j - 1), getDP(i-1, j - 1)) + 1;
     return dp[n - 1][m - 1];
    }
 
    private int min(int a, int b, int c) {
     return Math.min(Math.min(a, b),c);
  }
 
    int getDP(int i, int j) {
        if (i <0 && j <0)
         return 0;
       if(i<0)
          return j+1;
     if(j<0)
          return i+1;
     else 
           return dp[i][j];
    }
 
    public static int getStringDistance(String s1, String s2) {
      StringDistance obj = new StringDistance();
      return obj.getStringSimilar(s1, s2);
    }
    public void testGetStringSimilar(){
       assertEquals(3,getStringSimilar("kitten", "sitting"));
   }
    
}