From 8c0c14f40678295172e88faea4a3359e0b432c24 Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Mon, 12 Aug 2024 12:46:02 +0200
Subject: [PATCH] =?UTF-8?q?go:=20add=20=C2=AB1466.=20Reorder=20Routes=20to?=
 =?UTF-8?q?=20Make=20All=20Paths=20Lead=20to=20the=20City=20Zero=C2=BB?=
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Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 ...to-make-all-paths-lead-to-the-city-zero.go | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 go/reorder-routes-to-make-all-paths-lead-to-the-city-zero.go

diff --git a/go/reorder-routes-to-make-all-paths-lead-to-the-city-zero.go b/go/reorder-routes-to-make-all-paths-lead-to-the-city-zero.go
new file mode 100644
index 0000000..e43119d
--- /dev/null
+++ b/go/reorder-routes-to-make-all-paths-lead-to-the-city-zero.go
@@ -0,0 +1,57 @@
+package main
+
+const (
+	DIRECT  = 1
+	REVERSE = 0
+)
+
+type Edge struct {
+	neighbor int
+	edgeType int
+}
+
+func minReorder(n int, connections [][]int) int {
+	var dfs func(int, int)
+	makeGraph := func() map[int]([]Edge) {
+		g := make(map[int]([]Edge))
+
+		for _, edge := range connections {
+			u, v := edge[0], edge[1]
+
+			neighbors, present := g[u]
+			if !present {
+				neighbors = make([]Edge, 0)
+			}
+			g[u] = append(neighbors, Edge{neighbor: v, edgeType: DIRECT})
+
+			neighbors, present = g[v]
+			if !present {
+				neighbors = make([]Edge, 0)
+			}
+			g[v] = append(neighbors, Edge{neighbor: u, edgeType: REVERSE})
+		}
+
+		return g
+	}
+
+	graph := makeGraph()
+
+	count := 0
+	dfs = func(parent, node int) {
+		neighbors, found := graph[node]
+		if !found {
+			return
+		}
+
+		for _, edge := range neighbors {
+			if edge.neighbor != parent {
+				count += edge.edgeType
+				dfs(node, edge.neighbor)
+			}
+		}
+	}
+
+	dfs(-1, 0)
+
+	return count
+}