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

解法

func spiralOrder(matrix [][]int) []int {
	rowEnd := len(matrix) - 1
	colEnd := len(matrix[0]) - 1
	rowBegin := 0
	colBegin := 0
	ans := []int{}

	for rowBegin <= rowEnd && colBegin <= colEnd {
		for i := colBegin; i <= colEnd; i++ {
			ans = append(ans, matrix[rowBegin][i])
		}
		rowBegin++

		for i := rowBegin; i <= rowEnd; i++ {
			ans = append(ans, matrix[i][colEnd])
		}
		colEnd--

		if rowBegin <= rowEnd {
			for i := colEnd; i >= colBegin; i-- {
				ans = append(ans, matrix[rowEnd][i])
			}
		}
		rowEnd--

		if colBegin <= colEnd {
			for i := rowEnd; i >= rowBegin; i-- {
				ans = append(ans, matrix[i][colBegin])
			}
		}
		colBegin++
	}

	fmt.Println(ans)
	return ans
}