comefrom: <awangdev>72. Edit Distance_2.java
code: public int minDistance(String word1, String word2) {
          if (word1 == null && word2 == null) return 0;
          if (word1 == null || word2 == null) return word1 == null ? word2.length() : word1.length();
          
          int m = word1.length();
          int n = word2.length();
          int[][] dp = new int[2][n + 1];
          
          for (int i = 0; i <= m; i++) {
              for (int j = 0; j <= n; j++) {
                  if (i == 0) {
                      dp[i%2][j] = j;
                      continue;
                  }
                  if (j == 0) {
                      dp[i%2][j] = i;
                      continue;
                  }
                  if (word1.charAt(i - 1) == word2.charAt(j - 1)) {
                      dp[i%2][j] = dp[(i - 1)%2][j - 1];
                  } else { 
                      dp[i%2][j] = Math.min(dp[(i - 1)%2][j - 1], Math.min(dp[i%2][j - 1], dp[(i - 1)%2][j])) + 1;
                  }
              }
          }
          return dp[m%2][n];
      }
masked: public int sample_funcname ( String var_1 , String var_2 ) {
    if ( var_1 == null && var_2 == null ) return 0 ;
    if ( var_1 == null || var_2 == null ) return var_1 == null ? var_2 . length ( ) : var_1 . length ( ) ;
    int var_6 = var_1 . length ( ) ;
    int var_7 = var_2 . length ( ) ;
    int [ ] [ ] var_10 = new int [ 2 ] [ var_7 + 1 ] ;
    for ( int var_11 = 0 ;
    var_11 <= var_6 ;
    var_11 ++ ) {
      for ( int var_12 = 0 ;
      var_12 <= var_7 ;
      var_12 ++ ) {
        if ( var_11 == 0 ) {
          var_10 [ var_11 % 2 ] [ var_12 ] = var_12 ;
          continue ;
        }
        if ( var_12 == 0 ) {
          var_10 [ var_11 % 2 ] [ var_12 ] = var_11 ;
          continue ;
        }
        if ( var_1 . charAt ( var_11 - 1 ) == var_2 . charAt ( var_12 - 1 ) ) {
          var_10 [ var_11 % 2 ] [ var_12 ] = var_10 [ ( var_11 - 1 ) % 2 ] [ var_12 - 1 ] ;
        }
        else {
          var_10 [ var_11 % 2 ] [ var_12 ] = Math . min ( var_10 [ ( var_11 - 1 ) % 2 ] [ var_12 - 1 ] , Math . min ( var_10 [ var_11 % 2 ] [ var_12 - 1 ] , var_10 [ ( var_11 - 1 ) % 2 ] [ var_12 ] ) ) + 1 ;
        }
      }
    }
    return var_10 [ var_6 % 2 ] [ var_7 ] ;
  }
  