Rotate Image | 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.
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]]
Constraints:
n == matrix.length == matrix[i].length
1 <= n <= 20
-1000 <= matrix[i][j] <= 1000
Rotate Image Solutions
✅Time:O(n2)
✅Space: O(1)
C++
class Solution {
public:
void rotate(vector<vector<int>>& matrix) {
reverse(begin(matrix), end(matrix));
for (int i = 0; i < matrix.size(); ++i)
for (int j = i + 1; j < matrix.size(); ++j)
swap(matrix[i][j], matrix[j][i]);
}
};
Java
class Solution {
public void rotate(int[][] matrix) {
for (int i = 0, j = matrix.length - 1; i < j; ++i, --j) {
int[] temp = matrix[i];
matrix[i] = matrix[j];
matrix[j] = temp;
}
for (int i = 0; i < matrix.length; ++i)
for (int j = i + 1; j < matrix.length; ++j) {
final int temp = matrix[i][j];
matrix[i][j] = matrix[j][i];
matrix[j][i] = temp;
}
}
}
Python
class Solution {
public void rotate(int[][] matrix) {
for (int i = 0, j = matrix.length - 1; i < j; ++i, --j) {
int[] temp = matrix[i];
matrix[i] = matrix[j];
matrix[j] = temp;
}
for (int i = 0; i < matrix.length; ++i)
for (int j = i + 1; j < matrix.length; ++j) {
final int temp = matrix[i][j];
matrix[i][j] = matrix[j][i];
matrix[j][i] = temp;
}
}
}
Watch Tutorial
Checkout more Solutions here