## Array - 48. Rotate Image

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1. Rotate Image

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]
]
``````

go：

``````func rotate(matrix [][]int)  {
if matrix == nil || len(matrix) == 0 {
return
}

m := len(matrix)
n := len(matrix[0])

top := 0
left := 0
bottom := m - 1
right := n - 1

for top < bottom {
for j := 0; j < right - left; j++ {
tmp := matrix[top][left+j]

matrix[top][left+j] = matrix[bottom - j][left]
matrix[bottom - j][left] = matrix[bottom][right - j]
matrix[bottom][right - j] = matrix[top + j][right]
matrix[top + j][right] = tmp
}

top++
left++
bottom--
right--
}

return
}
``````