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103 lines
3.1 KiB
Markdown
103 lines
3.1 KiB
Markdown
---
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id: 69b5b2be76ec8135a7fbe974
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title: "Challenge 245: Spiral Matrix"
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challengeType: 29
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dashedName: challenge-245
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---
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# --description--
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Given a 2D matrix, return a flat array with all of its values in clockwise order.
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The returned array should have the top-left value first, move right along the top row, then down the right column, then left along the bottom row, then up the left column. Repeat inward for any remaining layers.
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For example, given:
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```json
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[
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[1, 2, 3],
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[4, 5, 6],
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[7, 8, 9]
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]
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```
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Return `[1, 2, 3, 6, 9, 8, 7, 4, 5]`.
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# --hints--
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`spiral_matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])` should return `[1, 2, 3, 6, 9, 8, 7, 4, 5]`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(spiral_matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]), [1, 2, 3, 6, 9, 8, 7, 4, 5])`)
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}})
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```
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`spiral_matrix([["a", "b", "c", "d"], ["l", "m", "n", "e"], ["k", "p", "o", "f"], ["j", "i", "h", "g"]])` should return `["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p"]`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(spiral_matrix([["a", "b", "c", "d"], ["l", "m", "n", "e"], ["k", "p", "o", "f"], ["j", "i", "h", "g"]]), ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p"])`)
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}})
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```
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`spiral_matrix([[True, False, False], [False, True, True], [False, True, False], [True, True, False]])` should return `[True, False, False, True, False, False, True, True, False, False, True, True]`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(spiral_matrix([[True, False, False], [False, True, True], [False, True, False], [True, True, False]]), [True, False, False, True, False, False, True, True, False, False, True, True])`)
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}})
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```
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`spiral_matrix([[25, 24, 23, 22, 21], [10, 9, 8, 7, 20], [11, 2, 1, 6, 19], [12, 3, 4, 5, 18], [13, 14, 15, 16, 17]])` should return `[25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1]`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(spiral_matrix([[25, 24, 23, 22, 21], [10, 9, 8, 7, 20], [11, 2, 1, 6, 19], [12, 3, 4, 5, 18], [13, 14, 15, 16, 17]]), [25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1])`)
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}})
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```
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# --seed--
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## --seed-contents--
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```py
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def spiral_matrix(matrix):
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return matrix
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```
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# --solutions--
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```py
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def spiral_matrix(matrix):
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result = []
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top, bottom = 0, len(matrix) - 1
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left, right = 0, len(matrix[0]) - 1
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while top <= bottom and left <= right:
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for i in range(left, right + 1):
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result.append(matrix[top][i])
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top += 1
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for i in range(top, bottom + 1):
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result.append(matrix[i][right])
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right -= 1
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if top <= bottom:
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for i in range(right, left - 1, -1):
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result.append(matrix[bottom][i])
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bottom -= 1
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if left <= right:
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for i in range(bottom, top - 1, -1):
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result.append(matrix[i][left])
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left += 1
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return result
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```
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