add new solutions

solutions/2/q211/solution.go

@@ -0,0 +1,63 @@
+package q211
+
+type TrieNode struct {
+	word bool
+	next [26]*TrieNode
+}
+
+func (n *TrieNode) hasMatch(pattern string, offset int) bool {
+	if n == nil {
+		return false
+	}
+	if offset == len(pattern) {
+		return n.word
+	}
+
+	c := pattern[offset]
+	if c != '.' {
+		return n.next[toIdx(c)].hasMatch(pattern, offset+1)
+	}
+
+	// Wildcard character
+	for _, t := range n.next {
+		if t != nil && t.hasMatch(pattern, offset+1) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func toIdx(b byte) int8 { return int8(b - 'a') }
+
+type WordDictionary struct{ root *TrieNode }
+
+func Constructor() WordDictionary {
+	return WordDictionary{
+		root: &TrieNode{},
+	}
+}
+
+func (d *WordDictionary) AddWord(word string) {
+	curr := d.root
+	for i := range len(word) {
+		c := word[i]
+		idx := toIdx(c)
+		if curr.next[idx] == nil {
+			curr.next[idx] = &TrieNode{}
+		}
+		curr = curr.next[idx]
+	}
+	curr.word = true
+}
+
+func (d *WordDictionary) Search(word string) bool {
+	return d.root.hasMatch(word, 0)
+}
+
+/**
+ * Your WordDictionary object will be instantiated and called as such:
+ * obj := Constructor();
+ * obj.AddWord(word);
+ * param_2 := obj.Search(word);
+ */

solutions/2/q236/solution.go

@@ -0,0 +1,31 @@
+package q236
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode {
+	if root == nil {
+		return nil
+	}
+	if root == p || root == q {
+		return root
+	}
+
+	l := lowestCommonAncestor(root.Left, p, q)
+	r := lowestCommonAncestor(root.Right, p, q)
+
+	switch {
+	case l == nil && r == nil:
+		return nil
+	case l != nil && r != nil:
+		return root
+	case l != nil:
+		return l
+	}
+	return r
+}
+
+var _ = lowestCommonAncestor