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Leetcode 54 Python Solution

Spiral Matrix

spiral_matrix

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:

class Solution:
    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
        ROWS, COLS = len(matrix), len(matrix[0])
        top, left = 0, 0
        right, bottom = COLS, ROWS
        res = []
        while left < right and top < bottom:
            # get every i in top row
            for i in range(left, right):
                res.append(matrix[top][i])
            top += 1
            # get every i in right column
            for i in range(top, bottom):
                res.append(matrix[i][right - 1])
            right -= 1
            
            if not (top < bottom and left < right):
                break
            # get every i in bottom row
            for i in range(right - 1, left - 1, -1):
                res.append(matrix[bottom - 1][i])
            bottom -= 1
            # get every i in left col
            for i in range(bottom - 1, top - 1, -1):
                res.append(matrix[i][left])
            left += 1
            
        return res

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Ashwini Verma on Jan 31, 2022 at 08:01 am


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