My Python3 solution. The rationale is that for each onion layer: 1. Get a list of coordinates on this layer (
dst) 2. Rotate this list of coordinates to make a new list (src) 3. For each coordinate indst, set the value of this coordinate in the output matrix to the value of the correspondingsrccoordinate in the original matrixdef get_layer_points( m: int, n: int, layer: int, ) -> list[tuple[int, int]]: points: list[tuple[int, int]] = [] for row in range(layer, m - layer - 1): points.append((row, layer)) for col in range(layer, n - layer - 1): points.append((m - layer - 1, col)) for row in range(m - layer - 1, layer, -1): points.append((row, n - layer - 1)) for col in range(n - layer - 1, layer, -1): points.append((layer, col)) return points def matrixRotation(matrix: list[list[int]], r: int): # Write your code here m = len(matrix) n = len(matrix[0]) output = [line.copy() for line in matrix] for layer in range(min(m, n) // 2): dst = get_layer_points(m, n, layer) steps = r % len(dst) src = dst[-steps:] + dst[:-steps] for i in range(len(dst)): output[dst[i][0]][dst[i][1]] = matrix[src[i][0]][src[i][1]] for line in output: print(*line, sep=" ")
My C#. All test cases now passing. Uses 'strands' wrapping around each 'shell'. These are unwrapped, rotated and then reassembled to make the final grid.
public static void matrixRotation(List<List<int>> matrix, int r) { int shells = Math.Min(matrix.Count, matrix[0].Count) / 2; var strands = new List<List<int>>(); for (int shell = 0; shell < shells; shell++) { var strand = new List<int>(); int col; int row = shell; // East for (col=shell; col < matrix[row].Count - shell; col++) { strand.Add(matrix[row][col]); } // South col -= 1; for (row = shell+1; row < matrix.Count - shell; row++) { strand.Add(matrix[row][col]); } // West row -= 1; for (col = matrix[row].Count - shell - 2; col >= shell; col--) { strand.Add(matrix[row][col]); } // North col += 1; for (row = matrix.Count - shell - 2; row > shell; row--) { strand.Add(matrix[row][col]); } for (int rotation = 0; rotation < (r % strand.Count); rotation++) { int first = strand[0]; strand.RemoveAt(0); strand.Add(first); } strands.Add(strand); } /* foreach (var strand in strands) { foreach (var item in strand) Console.Write(item + " "); Console.WriteLine(); } Console.WriteLine(); */ var result = new int[matrix.Count,matrix[0].Count]; for (int shell = 0; shell < shells; shell++) { int col; int row = shell; int n = 0; // East for (col = shell; col < matrix[row].Count - shell; col++) { result[row, col] = strands[shell][n]; n++; } // South col -= 1; for (row = shell + 1; row < matrix.Count - shell; row++) { result[row, col] = strands[shell][n]; n++; } // West row -= 1; for (col = matrix[row].Count - shell - 2; col >= shell; col--) { result[row, col] = strands[shell][n]; n++; } // North col += 1; for (row = matrix.Count - shell - 2; row > shell; row--) { result[row, col] = strands[shell][n]; n++; } } for (int row = 0; row < matrix.Count; row++) { for (int col = 0; col < matrix[0].Count; col++) { Console.Write(result[row, col] + " "); } Console.WriteLine(); } } }
Python 3
def matrixRotation(matrix, r): # Write your code here circles = min(len(matrix), len(matrix[0])) m, n = len(matrix), len(matrix[0]) _matrix = matrix.copy() for circle in range((int) (circles/2)): _m = (m - 2 * circle) - 1 _n = (n - 2 * circle) - 1 # print(_m,_n, circle) snake = [] snake.extend([matrix[i][circle] for i in range(circle, circle + _m)]) snake.extend([matrix[circle + _m][i] for i in range(circle, circle + _n)]) snake.extend([matrix[i][circle + _n] for i in range(circle + _m, circle, -1)]) snake.extend([matrix[circle][i] for i in range(circle + _n, circle, -1)]) # print(snake) _r = r % len(snake) snake = deque(snake) snake.rotate(_r) idx = 0 for i in range(circle, circle + _m): _matrix[i][circle] = snake[idx] idx += 1 for i in range(circle, circle + _n): _matrix[circle + _m][i] = snake[idx] idx += 1 for i in range(circle + _m, circle, -1): _matrix[i][circle + _n] = snake[idx] idx += 1 for i in range(circle + _n, circle, -1): _matrix[circle][i] = snake[idx] idx += 1 # print(_matrix) for i in range(m): print(" ".join([str(x) for x in _matrix[i]]))
Python 3 code
def matrixRotation(matrix, r): m = len(matrix) n = len(matrix[1]) m2 = [([0] * n) for i in range(m)] number_of_rings = min(int(m/2), int(n/2)) m_rings = [] n_rings = [] #creating a list of ring indexes for i in range(number_of_rings): elements_in_a_ring = 2*n + 2*(m-2) m_arr = [] n_arr = [] for j in range(n): m_arr.append(i) n_arr.append(n-j-1+i) for j in range(m-1): m_arr.append(j+1+i) n_arr.append(i) for j in range(n-1): m_arr.append(m-1+i) n_arr.append(j+1+i) for j in range(m-2): m_arr.append(m-j-2+i) n_arr.append(n-1+i) #Rotating index ring by r m_arr = [m_arr[(i-r) % len(m_arr)] for i, x in enumerate(m_arr)] n_arr = [n_arr[(i-r) % len(n_arr)] for i, x in enumerate(n_arr)] m_rings.append(m_arr) n_rings.append(n_arr) m -= 2 n -= 2 # print(f"m rings after: {m_rings}") # print(f"n rings after : {n_rings}") m = len(matrix) n = len(matrix[1]) matr2 = [([0] * n) for i in range(m)] #assign the data to the new matrix (matr2), from the data matrix (matrix) using the rotated data indexes for i in range(number_of_rings): elements_in_a_ring = 2*n + 2*(m-2) for j in range(n): matr2[i][n-j-1+i] = matrix[m_rings[i][j]][n_rings[i][j]] for j in range(m-1): matr2[j+1+i][i] = matrix[m_rings[i][j+n]][n_rings[i][j+n]] for j in range(n-1): matr2[m-1+i][j+1+i] = matrix[m_rings[i][m+n-1+j]][n_rings[i][m+n-1+j]] for j in range(m-2): m_arr.append(m-j-2+i) n_arr.append(n-1+i) matr2[m-j-2+i][n-1+i] = matrix[m_rings[i][m+(2*n)-2+j]][n_rings[i][m+(2*n)-2+j]] m -= 2 n -= 2 # print(f"m matrix 1: {matrix}") # print(f"m matrix 2: {matr2}") m = len(matrix) for i in range(m): print(*matr2[i])
Python 3.
Eventhough this solution is short, it takes too many ierations to complete the totations. So some test cases will exceed the time limit. I also commentd anothor optimized solution, that works for every test case.
def matrixRotation(matrix, r): m = len(matrix) n = len(matrix[1]) m2 = [([0]*n) for i in range(m)] for turns in range(r): m2 = [([0] * n) for i in range(m)] for i in range(min(int(m/2), int(n/2))): m2[i][n-i-1] = matrix[i+1][n-i-1] m2[m-i-1][i] = matrix[m-i-2][i] for j in range(n-(2*i)-1): m2[i][i+j] = matrix[i][i+j+1] m2[m-i-1][i+j+1] = matrix[m-i-1][i+j] for k in range(m-(2*i)-1): m2[k+i+1][i] = matrix[k+i][i] m2[k+i][n-i-1] = matrix[k+i+1][n-i-1] matrix = m2 for i in range(m): print(*matrix[i])
Load more conversations
Sort 706 Discussions, By:
Please Login in order to post a comment