add new solutions

solutions/29/q2906/solution.go

@@ -0,0 +1,30 @@
+// 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