leetcode 48. Rotate Image
You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).
Note:
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:
Given input matrix =
[
[1,2,3],
[4,5,6],
[7,8,9]
],
rotate the input matrix in-place such that it becomes:
[
[7,4,1],
[8,5,2],
[9,6,3]
]
思路：
先把矩阵转置，然后将每一行反转
var rotate = function(matrix) {
for(var i=0;i<matrix.length;i++){
for(j=i+1;j<matrix.length;j++){
var temp=matrix[i][j];
matrix[i][j]=matrix[j][i];
matrix[j][i]=temp;
}
matrix[i].reverse();
}
};
