. [Swift] LeetCode1072 by column inversion to obtain the maximum number of lines and the like | Flip Columns For Maximum Number of Equal Rows

Original Address: https://www.cnblogs.com/strengthen/p/10962559.html 

Given a matrix consisting of 0s and 1s, we may choose any number of columns in the matrix and flip every cell in that column.  Flipping a cell changes the value of that cell from 0 to 1 or from 1 to 0.

Return the maximum number of rows that have all values equal after some number of flips.

Example 1:

Input: [[0,1],[1,1]]
Output: 1
Explanation: After flipping no values, 1 row has all values equal.

Example 2:

Input: [[0,1],[1,0]]
Output: 2
Explanation: After flipping values in the first column, both rows have equal values.

Example 3:

Input: [[0,0,0],[0,0,1],[1,1,0]]
Output: 2
Explanation: After flipping values in the first two columns, the last two rows have equal values.

Note:

1. 1 <= matrix.length <= 300
2. 1 <= matrix[i].length <= 300
3. All matrix[i].length's are equal
4. matrix[i][j] is 0 or 1

---

To a matrix composed of 0 and 1 by a number of predetermined  matrix, selected from any number of columns and turn each cell thereon. After inversion, the cell value from 0 to 1, or from 1 to 0.

After some maximum number of rows returned flip on line all values ​​are equal. 

Example 1:

Input: [[0,1], [1,1]] 
Output: 1 
Explanation: no inversion, row 1 all values are equal.

Example 2:

Input: [[0,1], [1,0]] 
Output: 2 
Explanation: after the rollover value of the first column, two rows by equal values.

Example 3:

Input: [[0,0,0], [0,0,1], [1,1,0]] 
Output: 2 
Explanation: the value after two inverted before, the two lines of equal values. 

prompt:

1. 1 <= matrix.length <= 300
2. 1 <= matrix[i].length <= 300
3. All  matrix[i].length are equal
4. matrix[i][j] Is  0 or 1

---

Runtime: 1508 ms

Memory Usage: 21.3 MB

 1 class Solution {
 2     func maxEqualRowsAfterFlips(_ matrix: [[Int]]) -> Int {
 3         var map:[String:Int] = [String:Int]()
 4         for x in matrix
 5         {
 6             var s:String = String()
 7             let flag:Int = x[0]
 8             for i in 0..<x.count
 9             {
10                 if x[i] == flag
11                 {
12                     s.append("1")
13                 }
14                 else
15                 {
16                     s.append("0")
17                 }
18             }
19             map[s,default:0] += 1
20         }
21         var result:Int = 0
22         for val in map.values
23         {
24             result = max(result,val)
25         }
26         return result
27     }
28 }