/**
* https://leetcode.com/problems/determine-whether-matrix-can-be-obtained-by-rotation/description/
*/
to rotate matrix 90 degrees clockwise we have to transpose and flip it
public static boolean findRotation(int[][] mat, int[][] target) {
int countFullRotationCircle = mat.length + 1;
for (int i = 0; i <= countFullRotationCircle; i++) {
int[][] flip = flip(mat); // or maybe transponse + flip
mat = transpose(flip);
if (isEqual(mat, target)) {
return true;
}
}
return false;
}
private static int[][] transpose(int[][] matrix) {
int[][] transposed = new int[matrix.length][matrix[0].length];
for (int i = 0; i < matrix.length; i++) {
for (int j = 0; j < matrix[0].length; j++) {
transposed[i][j] = matrix[j][i];
}
}
return transposed;
}
private static int[][] flip(int[][] matrix) {
int[][] flipped = new int[matrix.length][matrix[0].length];
for (int i = 0; i < matrix.length; i++) {
for (int j = 0; j < matrix[0].length; j++) {
int[] row = matrix[i];
flipped[i][j] = row[matrix[0].length - 1 - j];
}
}
return flipped;
}
private static boolean isEqual(int[][] mat1, int[][] mat2) {
for (int i = 0; i < mat1.length; i++) {
for (int j = 0; j < mat1[0].length; j++) {
if (mat1[i][j] != mat2[i][j]) {
return false;
}
}
}
return true;
}Example
