some more problems

prefix-and-suffix-search/sol.go

@@ -0,0 +1,109 @@
+package main
+
+type StringMap struct {
+	Map SubStringMap
+}
+
+func NewStringMap() *StringMap {
+	return &StringMap{
+		Map: map[byte]*StringMap{},
+	}
+}
+
+func (sm *StringMap) CombineAllSubStrings(prefix string, rev bool) []string {
+	if len(sm.Map) == 0 {
+		return []string{prefix}
+	}
+	out := []string{}
+	for chr, Map := range sm.Map {
+		if rev {
+			out = append(out, Map.CombineAllSubStrings(string(chr)+prefix, rev)...)
+		} else {
+			out = append(out, Map.CombineAllSubStrings(prefix+string(chr), rev)...)
+		}
+	}
+	return out
+}
+
+func (sm *StringMap) Add(word string, rev bool) {
+	if len(word) == 0 {
+		return
+	}
+	take := 0
+	if rev {
+		take = len(word) - 1
+	}
+	sub, ok := sm.Map[word[take]]
+	if !ok {
+		sub = NewStringMap()
+		sm.Map[word[take]] = sub
+	}
+	if rev {
+		sub.Add(word[:take], rev)
+	} else {
+		sub.Add(word[1:], rev)
+	}
+}
+
+type SubStringMap = map[byte]*StringMap
+
+type WordFilter struct {
+	Prefixes *StringMap
+	Suffixes *StringMap
+	Words    map[string]int
+}
+
+func Constructor(words []string) WordFilter {
+	Prefixes := NewStringMap()
+	Suffixes := NewStringMap()
+	Words := map[string]int{}
+
+	for idx, word := range words {
+		Words[word] = idx
+		Prefixes.Add(word, false)
+		Suffixes.Add(word, true)
+	}
+	return WordFilter{
+		Prefixes: Prefixes,
+		Suffixes: Suffixes,
+		Words:    Words,
+	}
+}
+
+func (wf *WordFilter) F(prefix, suffix string) int {
+	prefix_base, ok := wf.Prefixes, true
+	for i := range prefix {
+		prefix_base, ok = prefix_base.Map[prefix[i]]
+		if !ok {
+			return -1
+		}
+	}
+	suffix_base := wf.Suffixes
+	for i := len(suffix) - 1; i >= 0; i-- {
+		suffix_base, ok = suffix_base.Map[suffix[i]]
+		if !ok {
+			return -1
+		}
+	}
+	prefix_found := map[string]bool{}
+	for _, found := range prefix_base.CombineAllSubStrings(prefix, false) {
+		prefix_found[found] = true
+	}
+
+	max := -1
+	for _, found := range suffix_base.CombineAllSubStrings(suffix, true) {
+		if _, ok := prefix_found[found]; ok {
+			idx := wf.Words[found]
+			if idx > max {
+				max = idx
+			}
+		}
+	}
+	return max
+}
+
+/**
+ * Your WordFilter object will be instantiated and called as such:
+ * obj := Constructor(words);
+ * param_1 := obj.F(prefix,suffix);
+ */