Leetcode rotate-image

一開始看到題目，看到2維陣列就會有些緊張，想著是否要拆開，或是要如何從圖示去轉陣列，寫得很亂又雜還是解不出來。
看完其他教學才知道可以從斜對角開始調換，最後再將左右做調換。

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.

var rotate = function (matrix) {
  //斜對角
  for (let i = 0; i < matrix.length; i++) {
    for (let j = 0; j < matrix.length; j++) {
      let temp = matrix[i][j];
      matrix[i][j] = matrix[j][i];
      matrix[j][i] = temp;
    }
  }
  //reverse
  // Secondly Make Reflected Image Of Matrix
  for (let i = 0; i < matrix.length; i++) {
      //最左和最右調換，為兩兩調換，所以j的長度為matrix長度除以2
    for (let j = 0; j < matrix.length / 2; j++) {
      var Temp = matrix[i][j]
      //右側最後的值為長度-1
      matrix[i][j] = matrix[i][matrix.length - 1 - j]
      matrix[i][matrix.length - 1 - j] = Temp
    }
  }
  return matrix;
};

參考資料：
Rotate Image - LeetCode 48 - JavaScript