48.旋转图像

/**
 * @param {number[][]} matrix
 * @return {void} Do not return anything, modify matrix in-place instead.
 */
var rotate = function (matrix) {
    // 找规律
    // 输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
    // 输出：[[7,4,1],[8,5,2],[9,6,3]]
    // 输入：matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
    // 输出：[[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

    let len = matrix.length
    // 使用辅助数组
    let matrix_new = new Array(len).fill(0).map(e => new Array(len).fill(0))
    for (let i = 0; i < len; i++) {
        for (let j = 0; j < len; j++) {
            // 规律 matrix_new[j][len - i - 1] = matrix[i][j];
            matrix_new[j][len - i - 1] = matrix[i][j];
        }
    }
    for (let i = 0; i < len; i++) {
        for (let j = 0; j < len; j++) {
            matrix[i][j] = matrix_new[i][j];
        }
    }
    return matrix
};