54. 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

# @lc code=start
using LeetCode

function spiral_order(matrix::Vector{Vector{Int}})::Vector{Int}
    res = Int[]
    while !isempty(matrix)
        for each in popfirst!(matrix)
            push!(res, each)
        end

        if !isempty(matrix) && !isempty(matrix[1])
            for row in matrix
                push!(res, pop!(row))
            end
        end

        if !isempty(matrix)
            for each in pop!(matrix)[end:-1:1]
                push!(res, each)
            end
        end

        if !isempty(matrix) && !isempty(matrix[1])
            for row in matrix[end:-1:1]
                push!(res, popfirst!(row))
            end
        end
    end

    return res
end
# @lc code=end

spiral_order (generic function with 1 method)

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