48. Rotate Image

You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

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:

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

Example 2:

Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

Example 3:

Input: matrix = [[1]]
Output: [[1]]

Example 4:

Input: matrix = [[1,2],[3,4]]
Output: [[3,1],[4,2]]

Constraints:

• matrix.length == n
• matrix[i].length == n
• 1 <= n <= 20
• -1000 <= matrix[i][j] <= 1000

# @lc code=start
using LeetCode

function rotate_48(matrix::Matrix{Int})
    n = size(matrix, 1)
    for i in 1:div(n, 2), j in i:(n - i)
        matrix[i, j], matrix[j, n + 1 - i], matrix[n + 1 - i, n + 1 - j], matrix[n + 1 - j, i] = matrix[
            n + 1 - j, i
        ],
        matrix[i, j], matrix[j, n + 1 - i],
        matrix[n + 1 - i, n + 1 - j]
    end
    return matrix
end
# @lc code=end

rotate_48 (generic function with 1 method)

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