LC054 - Spiral Matrix

Problem

Given an m x n matrix, return all elements of the matrix in spiral order.

Example

Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]

Output: [1,2,3,6,9,8,7,4,5]

Solution

Time and space complexity of solution is $O(m\cdot n)$

def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
	res = []
	left, right = 0, len(matrix[0])
	top, bottom = 0, len(matrix)

	while left < right and top < bottom:
		for i in range(left, right):
			res.append(matrix[top][i])
		top += 1
		for i in range(top, bottom):
			res.append(matrix[i][right-1])
		right -= 1
		if not (left < right and top < bottom):
			break
		for i in range(right - 1, left - 1, -1):
			res.append(matrix[bottom-1][i])
		bottom -= 1
		for i in range(bottom - 1, top - 1, -1):
			res.append(matrix[i][left])
		left += 1
	return res