LeetCode Top Interview 150

54. Spiral Matrix

Medium

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

Example 1:

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

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

Example 2:

Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]

Output: [1,2,3,4,8,12,11,10,9,5,6,7]

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 10
• -100 <= matrix[i][j] <= 100

Solution

from typing import List

class Solution:
    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
        result = []
        r = 0
        c = 0
        big_r = len(matrix) - 1
        big_c = len(matrix[0]) - 1
        while r <= big_r and c <= big_c:
            for i in range(c, big_c + 1):
                result.append(matrix[r][i])
            r += 1
            for i in range(r, big_r + 1):
                result.append(matrix[i][big_c])
            big_c -= 1
            if r <= big_r:
                for i in range(big_c, c - 1, -1):
                    result.append(matrix[big_r][i])
                big_r -= 1
            if c <= big_c:
                for i in range(big_r, r - 1, -1):
                    result.append(matrix[i][c])
                c += 1
        return result

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