From c911ab1f19feeec699b6154e2e49afba5411f8c7 Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Sun, 21 Jul 2024 23:13:29 +0200
Subject: [PATCH] =?UTF-8?q?go:=20add=20=C2=AB2392.=20Build=20a=20Matrix=20?=
 =?UTF-8?q?With=20Conditions=C2=BB?=
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Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 go/build-a-matrix-with-conditions.go | 68 ++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 go/build-a-matrix-with-conditions.go

diff --git a/go/build-a-matrix-with-conditions.go b/go/build-a-matrix-with-conditions.go
new file mode 100644
index 0000000..7101abe
--- /dev/null
+++ b/go/build-a-matrix-with-conditions.go
@@ -0,0 +1,68 @@
+package main
+
+import aq "github.com/emirpasic/gods/v2/queues/arrayqueue"
+
+func buildMatrix(k int, rowConditions [][]int, colConditions [][]int) [][]int {
+	toposort := func(edges [][]int, n int) []int {
+		neighbours := make([][]int, n+1)
+		for i := range n + 1 {
+			neighbours[i] = []int{}
+		}
+
+		degrees, order := make([]int, n+1), make([]int, n)
+		for _, edge := range edges {
+			u, v := edge[0], edge[1]
+
+			neighbours[u] = append(neighbours[u], v)
+			degrees[v]++
+		}
+
+		queue := aq.New[int]()
+		for i := 1; i <= n; i++ {
+			if degrees[i] == 0 {
+				queue.Enqueue(i)
+			}
+		}
+
+		idx := 0
+		for !queue.Empty() {
+			u, _ := queue.Dequeue()
+			order[idx] = u
+
+			n--
+			for _, v := range neighbours[u] {
+				degrees[v]--
+				if degrees[v] == 0 {
+					queue.Enqueue(v)
+				}
+			}
+
+			idx++
+		}
+
+		if n != 0 {
+			return []int{}
+		}
+		return order
+	}
+
+	rowOrder, colOrder := toposort(rowConditions, k), toposort(colConditions, k)
+	if len(rowOrder) == 0 || len(colOrder) == 0 {
+		return [][]int{}
+	}
+
+	matrix := make([][]int, k)
+	for i := range k {
+		matrix[i] = make([]int, k)
+	}
+
+	for row := range k {
+		for col := range k {
+			if rowOrder[row] == colOrder[col] {
+				matrix[row][col] = rowOrder[row]
+			}
+		}
+	}
+
+	return matrix
+}