You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).
By using the relation "matrix[i][j] = matrix[n-1-j][i]", we can loop through the matrix.
public void rotate(int[][] matrix) {
int n = matrix.length;
for (int i = 0; i < n / 2; i++) {
for (int j = 0; j < Math.ceil(((double) n) / 2.); j++) {
int temp = matrix[i][j];
matrix[i][j] = matrix[n-1-j][i];
matrix[n-1-j][i] = matrix[n-1-i][n-1-j];
matrix[n-1-i][n-1-j] = matrix[j][n-1-i];
matrix[j][n-1-i] = temp;
}
}
}
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LeetCode – Rotate Image (Java)
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