====
思路：
1. 对角线翻折
i = 0 ; i<matrix.length
j = i ; j < matrix.length
matrix[i][j] matrix[j][i] = matrix[j][i] matrix[i][j]2. 左右翻折
i = 0 i<matrix.length
j = 0 j < Math.floor(matrix.length/2)
matrix[i][j] matrix[i][matrix.length-1-j] = matrix[i][matrix.length-i-j] matrix[i][j]
