[Swift]LeetCode48. 旋轉圖像 | Rotate Image

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You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Note:

You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.

Example 1:

Given input matrix = 
[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],
rotate the input matrix in-place such that it becomes:
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]

Example 2:

Given input matrix =
[
  [ 5, 1, 9,11],
  [ 2, 4, 8,10],
  [13, 3, 6, 7],
  [15,14,12,16]
], 
rotate the input matrix in-place such that it becomes:
[
  [15,13, 2, 5],
  [14, 3, 4, 1],
  [12, 6, 8, 9],
  [16, 7,10,11]
]

---

給定一個 n × n 的二維矩陣表示一個圖像。

將圖像順時針旋轉 90 度。

說明：

你必須在原地旋轉圖像，這意味着你須要直接修改輸入的二維矩陣。請不要使用另外一個矩陣來旋轉圖像。

示例 1:

給定 matrix = 
[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],
原地旋轉輸入矩陣，使其變爲:
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]

示例 2:

給定 matrix =
[
  [ 5, 1, 9,11],
  [ 2, 4, 8,10],
  [13, 3, 6, 7],
  [15,14,12,16]
], 
原地旋轉輸入矩陣，使其變爲:
[
  [15,13, 2, 5],
  [14, 3, 4, 1],
  [12, 6, 8, 9],
  [16, 7,10,11]
]

---

8ms

 1 class Solution 
 2 {
 3     func rotate(_ matrix: inout [[Int]]) 
 4     {
 5         let temp = matrix;
 6         
 7         for i in 0..<matrix.count
 8         {
 9             for j in 0..<matrix[0].count
10             {
11                 matrix[j][matrix[0].count - 1 - i] = temp[i][j];
12             }
13         }
14     }
15 }

---

12ms

 1 class Solution {
 2     func rotate(_ matrix: inout [[Int]]) {    
 3         matrix.reverse()
 4         
 5         for i in 1..<matrix.count {
 6             for j in 0..<i {
 7                 (matrix[i][j], matrix[j][i]) = (matrix[j][i], matrix[i][j])
 8             }
 9         }
10     }
11 }

---

16ms

 1 class Solution {
 2     func rotate(_ matrix: inout [[Int]]) {
 3         let layers:Int = matrix.count / 2 - 1
 4         let n = matrix.count - 1
 5         var currentLayerWidth = n - 1    //layer的寬度,每一層轉 currentLayerWidth次
 6         if layers < 0 {
 7             return 
 8         }
 9         for i in 0...layers {
10             if currentLayerWidth < 0 {
11                 break
12             }
13             for j in 0...currentLayerWidth {  //每層旋轉邏輯
14                 let x = i + j          //i 層級,x 移動點（相對整個矩陣）
15                 let firstPoint = matrix[i][x]
16                 matrix[i][x] = matrix[n - x][i]
17                 matrix[n - x][i] = matrix[n - i][n - x]
18                 matrix[n - i][n - x] = matrix[x][n - i]
19                 matrix[x][n - i] = firstPoint
20             }
21             //向內層靠近
22             currentLayerWidth = currentLayerWidth - 2
23         }
24     }
25 }

---

16ms

 1 class Solution {
 2     func rotate(_ matrix: inout [[Int]]) {
 3         let n = matrix.count
 4         
 5         for layer in 0..<n/2 {
 6             let start = layer
 7             let end = n - layer - 1
 8             
 9             for i in start..<end {
10                 let offset = i - start
11                 (matrix[start][i], matrix[i][end], matrix[end][end-offset], matrix[end-offset][start]) = ( matrix[end-offset][start], matrix[start][i], matrix[i][end], matrix[end][end-offset])
12             }
13         }
14     }
15 }

---

20ms

 1 class Solution {
 2     func rotate(_ matrix: inout [[Int]]) {
 3         let count = matrix[0].count
 4         for i in (0 ..< count)  {
 5             for t in (i ..< count) {
 6                 let d = matrix[t][i]
 7                 matrix[t][i] = matrix[i][t]
 8                 matrix[i][t] = d 
 9             }
10         }
11 
12         for i in (0 ..< count) {
13             for t in (0 ..< (count + 1)/2 ) {
14                 let temp = matrix[i][t]
15                 matrix[i][t] = matrix[i][count - t - 1]
16                 matrix[i][count - t - 1] = temp
17             }
18         }
19     }
20 }

---

28ms

 1 class Solution {
 2     func rotate(_ matrix: inout [[Int]]) {
 3         let count = matrix.count
 4         for i in 0..<count {
 5             for j in i+1..<count {
 6                 if i == j { return }
 7                 // swap
 8                 matrix[i][j] = matrix[i][j] ^ matrix[j][i]
 9                 matrix[j][i] = matrix[i][j] ^ matrix[j][i]
10                 matrix[i][j] = matrix[i][j] ^ matrix[j][i]
11             }
12             matrix[i].reverse()
13         }
14     }
15 }

---

36ms

 1 class Solution {
 2     func rotate(_ matrix: inout [[Int]]) {
 3 
 4         for item in 0...matrix.count-1 {
 5             for i in item...matrix.count-1 {
 6                 let tmpItem = matrix[item][i]
 7                 matrix[item][i] = matrix[i][item]
 8                 matrix[i][item] = tmpItem
 9             }
10         }
11         for item in 0...matrix.count-1 {
12             matrix[item].reverse()
13         }
14         
15     }
16 }