go: add «3043. Find the Length of the Longest Common Prefix»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/find-the-length-of-the-longest-common-prefix.go

@@ -0,0 +1,42 @@
+package main
+
+import "strconv"
+
+type LCPTrieNode struct {
+	children [10]*LCPTrieNode
+	has      [2]bool
+}
+
+func longestCommonPrefix(arr1 []int, arr2 []int) int {
+	update := func(node *LCPTrieNode, number string, index int) int {
+		best := 0
+		for i := range number {
+			child := number[i] - '0'
+			if node.children[child] == nil {
+				node.children[child] = &LCPTrieNode{}
+			}
+			node = node.children[child]
+			node.has[index] = true
+
+			if node.has[index] && node.has[(index+1)%2] {
+				best = i + 1
+			}
+		}
+
+		return best
+	}
+
+	root := LCPTrieNode{}
+	for _, num := range arr1 {
+		strnum := strconv.Itoa(num)
+		update(&root, strnum, 0)
+	}
+
+	longest := 0
+	for _, num := range arr2 {
+		strnum := strconv.Itoa(num)
+		longest = max(longest, update(&root, strnum, 1))
+	}
+
+	return longest
+}