Javascript(leetcode#48) Rotate Image

Difficult:Medium

題目

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.

翻譯

給定一個表示圖像的 n x n 2D 矩陣，將圖像旋轉 90 度（順時針）。

您必須就地旋轉圖像，這意味著您必須直接修改輸入的 2D 矩陣。不要分配另一個二維矩陣並進行旋轉。

範例

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]]

解題思路

1.規律 1到n的第1個index 從最後矩陣值依序填入
2.遵循規律繼續往前一個矩陣

Solution

Code 1 :

var rotate = function(matrix) {
  let newarr= JSON.parse(JSON.stringify(matrix));
  let x=0,y;
    for(let i=0;i<matrix.length;i++){
      y=matrix.length-1;
      for(let j=0;j<matrix[i].length;j++){
        matrix[i][j]=newarr[y][x];
        y--;
       
      }
      x++;
    }
    return matrix;
};