[Swift]LeetCode867. 轉置矩陣 | Transpose Matrix

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Given a matrix A, return the transpose of A.

The transpose of a matrix is the matrix flipped over it's main diagonal, switching the row and column indices of the matrix. 

Example 1:

Input: [[1,2,3],[4,5,6],[7,8,9]]
Output: [[1,4,7],[2,5,8],[3,6,9]] 

Example 2:

Input: [[1,2,3],[4,5,6]]
Output: [[1,4],[2,5],[3,6]] 

Note:

1. 1 <= A.length <= 1000
2. 1 <= A[0].length <= 1000

---

給定一個矩陣 A， 返回 A 的轉置矩陣。

矩陣的轉置是指將矩陣的主對角線翻轉，交換矩陣的行索引與列索引。 

示例 1：

輸入：[[1,2,3],[4,5,6],[7,8,9]]
輸出：[[1,4,7],[2,5,8],[3,6,9]]

示例 2：

輸入：[[1,2,3],[4,5,6]]
輸出：[[1,4],[2,5],[3,6]] 

提示：

1. 1 <= A.length <= 1000
2. 1 <= A[0].length <= 1000

---

Runtime: 92 ms

Memory Usage: 19 MB

 1 class Solution {
 2     func transpose(_ A: [[Int]]) -> [[Int]] {
 3         var tmp = Array(repeating: (Array(repeating:0, count: A.count)), count: A[0].count)
 4         for i in 0..<A[0].count {
 5             for j in 0..<A.count {
 6                 tmp[i][j] = A[j][i]
 7             }
 8         }
 9         
10         return tmp
11     }
12 }

---

Runtime: 92 ms

Memory Usage: 19.2 MB

 1 class Solution {
 2     func transpose(_ A: [[Int]]) -> [[Int]] {
 3         if A.count == 0 {
 4             return []
 5         }
 6         let count = A[0].count
 7         var R: [[Int]] = []
 8         for j in 0..<count {
 9           var r: [Int] = []
10             for i in 0..<A.count {
11                 r.append(A[i][j])
12             }
13             R.append(r)
14         }
15         
16         return R        
17     }
18 }

---

116ms

 1 class Solution {
 2 func transpose(_ A: [[Int]]) -> [[Int]] {
 3     var result: [[Int]] = []
 4     for i in 0..<A[0].count {
 5         result.append([])
 6         for j in 0..<A.count {
 7             result[i].append(A[j][i])
 8         }
 9     }
10     return result
11   }
12 }

---

124ms

 1 class Solution {
 2     func transpose(_ A: [[Int]]) -> [[Int]] {
 3         var x = A.count
 4         var y = A[0].count
 5         var result: [[Int]] = []
 6         
 7         for i in 0..<y {
 8             var list: [Int] = []
 9             for j in 0..<x {
10                 list += [A[j][i]]
11             }
12             result += [list]
13         }
14         
15         return result        
16     }
17 }

---

128ms

class Solution {
    func transpose(_ A: [[Int]]) -> [[Int]] {
        
        var row = -1
        var column = -1
        let result = Array(count: A[0].count) { () -> [Int] in
            row += 1
            column = -1
            return Array(count: A.count) { () -> Int in
                column += 1
                return A[column][row]
            }
        } 
        return result
    }
}

public extension Array {
    public init(count: Int, generator: @escaping() -> Element) {
        precondition(count >= 0, "arrays must have non-negative size")
        self.init((0..<count).lazy.map { Element in generator() })
    }
}