// Package q2906 implements a solution for https://leetcode.com/problems/construct-product-matrix/
package q2906

const MOD = 12345

func constructProductMatrix(grid [][]int) [][]int {
	w, h := len(grid[0]), len(grid)
	output := make([][]int, h)
	output[0] = make([]int, w*h)
	for i := h - 1; i >= 0; i-- {
		output[i] = output[0][i*w : (i+1)*w]
	}

	suffix := 1
	for i := w*h - 1; i >= 0; i-- {
		y, x := i/w, i%w
		output[y][x] = suffix
		suffix = suffix * grid[y][x] % MOD
	}

	prefix := 1
	for i := range w * h {
		y, x := i/w, i%w
		output[y][x] = output[y][x] * prefix % MOD
		prefix = prefix * grid[y][x] % MOD
	}
	return output
}

var _ = constructProductMatrix