931. Minimum Falling Path Sum

Given a square array of integers A, we want the minimum sum of a falling path through A.

A falling path starts at any element in the first row, and chooses one element from each row. The next row's choice must be in a column that is different from the previous row's column by at most one.

Example 1:

Input: [[1,2,3],[4,5,6],[7,8,9]]
Output: 12
Explanation:
The possible falling paths are:

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

The falling path with the smallest sum is [1,4,7], so the answer is 12.

Constraints:

• 1 <= A.length == A[0].length <= 100
• -100 <= A[i][j] <= 100

# @lc code=start
using LeetCode

function min_falling_path_sum(matrix::Vector{Vector{Int}})::Int
    n = length(matrix)
    function f(l1, l2)
        return [
            num + minimum(l1[max(i - 1, 1):min(i + 1, n)]) for (i, num) in enumerate(l2)
        ]
    end
    return minimum(foldl(f, matrix))
end

# @lc code=end

min_falling_path_sum (generic function with 1 method)

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