geeksforgeeks: add auto-complete feature

geeksforgeeks/auto-complete-feature/README.md

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+# Auto-complete feature
+
+We are given a Trie with a set of strings stored in it.
+Now the user types in a prefix of his search query,
+we need to give him all recommendations to auto-complete his query based on the strings stored in the Trie.
+
+## Copyright Notice
+
+This problem is based on [content](https://www.geeksforgeeks.org/auto-complete-feature-using-trie/)
+from [GeeksforGeeks](https://www.geeksforgeeks.org)
+written by Hemang Sarkar
+and subject to [GeeksforGeeks copyright](https://www.geeksforgeeks.org/legal/copyright-information/).
+The original content from GeeksforGeeks and any modifications made here are attributed to GeeksforGeeks contributors,
+and this work is shared under [CC BY-SA 4.0](../LICENSE).

geeksforgeeks/auto-complete-feature/solution.go

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+package auto_complete_feature
+
+const alphabetSize = 26 + 1
+
+func Solution(q string, dict []string) []string {
+	if q == "" {
+		return nil
+	}
+
+	root := newTrieNode()
+	for _, word := range dict {
+		root.insert(word)
+	}
+
+	return root.autoComplete(q)
+}
+
+type trieNode struct {
+	childs []*trieNode
+	isWord bool
+	isLeaf bool
+}
+
+func newTrieNode() *trieNode {
+	return &trieNode{
+		childs: make([]*trieNode, alphabetSize),
+	}
+}
+
+func (node *trieNode) insert(s string) {
+	if len(s) == 0 {
+		node.isLeaf = true
+		node.isWord = true
+		return
+	}
+
+	index := ctoi(rune(s[0]))
+	child := node.childs[index]
+	if child == nil {
+		child = newTrieNode()
+		node.childs[index] = child
+	}
+
+	child.isLeaf = false
+	child.insert(s[1:])
+}
+
+func (node *trieNode) autoComplete(s string) []string {
+	next := node
+	for _, r := range s {
+		next = next.childs[ctoi(r)]
+		if next == nil {
+			return nil
+		}
+	}
+
+	if next == nil {
+		return nil
+	}
+
+	return next.append(s)
+}
+
+func (node *trieNode) append(s string) []string {
+	var out []string
+	if node.isWord {
+		out = append(out, s)
+	}
+
+	for i, child := range node.childs {
+		if child == nil {
+			continue
+		}
+
+		prefix := s + string(itoc(rune(i)))
+
+		if child.isLeaf {
+			out = append(out, prefix)
+			continue
+		}
+
+		for _, word := range child.append(prefix) {
+			out = append(out, word)
+		}
+	}
+
+	return out
+}
+
+func itoc(i rune) rune {
+	switch i {
+	case 26:
+		return ' '
+	default:
+		return i + 'a'
+	}
+}
+
+func ctoi(c rune) rune {
+	switch c {
+	case ' ':
+		return 26
+	default:
+		return c - 'a'
+	}
+}

geeksforgeeks/auto-complete-feature/solution_test.go

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+package auto_complete_feature_test
+
+import (
+	"testing"
+
+	sut "github.com/minizilla/minmax/geeksforgeeks/auto-complete-feature"
+	"github.com/minizilla/testr"
+)
+
+func TestAutoCompleteFeature(t *testing.T) {
+	dict := []string{
+		"i am iron man",
+		"i am iron man endgame",
+		"i am iron man meme",
+		"i am venom",
+		"i am venom sound",
+		"i am venom morbius",
+		"i am batman",
+	}
+
+	tests := map[string]struct {
+		q   string
+		res []string
+	}{
+		"empty":          {"", nil},
+		"can't complete": {"i am man", nil},
+		"incomplete": {
+			"i am iro",
+			[]string{
+				"i am iron man",
+				"i am iron man endgame",
+				"i am iron man meme",
+			},
+		},
+		"incomplete with space": {
+			"i am venom ",
+			[]string{
+				"i am venom morbius",
+				"i am venom sound",
+			},
+		},
+		"complete": {
+			"i am batman",
+			[]string{
+				"i am batman",
+			},
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			assert := testr.New(t)
+			res := sut.Solution(tc.q, dict)
+			assert.Equal(res, tc.res)
+		})
+	}
+}