// Package q1594 implements a solution for https://leetcode.com/problems/maximum-non-negative-product-in-a-matrix/
package q1594

const MOD = 1e9 + 7

func maxProductPath(grid [][]int) int {
	buf := make([][2]int, len(grid[0]))

	buf[0] = [2]int{grid[0][0], grid[0][0]}
	for c := 1; c < len(grid[0]); c++ {
		num := grid[0][c]
		n1, n2 := num*buf[c-1][0], num*buf[c-1][1]
		buf[c] = [2]int{max(n1, n2), min(n1, n2)}
	}

	for r := 1; r < len(grid); r++ {
		num := grid[r][0]
		n1, n2 := num*buf[0][0], num*buf[0][1]
		buf[0] = [2]int{max(n1, n2), min(n1, n2)}

		for c := 1; c < len(grid[0]); c++ {
			num := grid[r][c]
			n1, n2 := num*buf[c][0], num*buf[c][1]
			n3, n4 := num*buf[c-1][0], num*buf[c-1][1]
			buf[c] = [2]int{
				max(n1, n2, n3, n4),
				min(n1, n2, n3, n4),
			}
		}
	}

	return max(-1, buf[len(buf)-1][0]%MOD)
}

var _ = maxProductPath