LeetCode-in-All

48. Rotate Image

Medium

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]]

Constraints:

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

Solution

impl Solution {
    pub fn rotate(matrix: &mut Vec<Vec<i32>>) {
        let n = matrix.len();
        for i in 0..n / 2 {
            for j in i..n - i - 1 {
                let pos = [
                    (i, j),
                    (j, n - 1 - i),
                    (n - 1 - i, n - 1 - j),
                    (n - 1 - j, i),
                ];

                let mut t = matrix[pos[0].0][pos[0].1];
                for k in 1..pos.len() {
                    let temp = matrix[pos[k].0][pos[k].1];
                    matrix[pos[k].0][pos[k].1] = t;
                    t = temp;
                }
                matrix[pos[0].0][pos[0].1] = t;
            }
        }
    }
}

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