rotateimage.js

/* 
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]]
*/


/**
 * @param {number[][]} matrix
 * @return {void} Do not return anything, modify matrix in-place instead.
 */
var rotate = function (matrix) {

    /*
        ip: [[1,2,3],[4,5,6],[7,8,9]]
        
        reverse array => [ [ 7, 8, 9 ], [ 4, 5, 6 ], [ 1, 2, 3 ] ]
        bring all 0 index of each array to 1st array
        bring all 1 index of each array to 2nd array
        bring all 2 index of each array to 3rd array
        
        op: [[7,4,1],[8,5,2],[9,6,3]]
    
    */
    let op = []
    let arrCpy = Array.from(matrix);
    let arr = arrCpy.reverse()

    for (let i = 0; i < arr.length; i++) {
        let sbArr = [];
        for (let j = 0; j < arr[i].length; j++) {
            sbArr.push(arr[j][i])
        }

        op.push(sbArr);
        matrix[i] = sbArr;
    }

    console.log("op ", op)

};