add new files

Author: anakin

235. Lowest Common Ancestor of a Binary Search Tree.go

@@ -0,0 +1,26 @@
+package main
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode {
+
+	if root == nil {
+		return nil
+	}
+
+	for root != nil {
+		if p.Val > root.Val && q.Val > root.Val {
+			root = root.Right
+		} else if p.Val < root.Val && q.Val < root.Val {
+			root = root.Left
+		} else {
+			return root
+		}
+	}
+	return nil
+
+}

236. Lowest Common Ancestor of a Binary Tree.go

@@ -0,0 +1,33 @@
+package main
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func lowestCommonAncestor(root, p, q *TreeNode) *TreeNode {
+	return helper(root, p, q)
+}
+
+func helper(root, p, q *TreeNode) *TreeNode {
+	if root == nil {
+		return nil
+	}
+	left := helper(root.Left, p, q)
+	right := helper(root.Right, p, q)
+	if root == p || root == q {
+		return root
+	}
+	if left != nil && right != nil {
+		return root
+	}
+
+	if left != nil && right == nil {
+		return left
+	}
+	if left == nil && right != nil {
+		return right
+	}
+	return nil
+}

237. Delete Node in a Linked List.go

@@ -0,0 +1,17 @@
+package main
+
+type ListNode struct {
+	Val  int
+	Next *TreeNode
+}
+
+func deleteNode(node *ListNode) {
+	if node == nil {
+		return
+	}
+	if node.Next == nil {
+		node = nil
+	}
+	node.Val = node.Next.Val
+	node.Next = node.Next.Next
+}

257. Binary Tree Paths.go

@@ -0,0 +1,31 @@
+package main
+
+import "strconv"
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func binaryTreePaths(root *TreeNode) []string {
+	s := []string{}
+	if root == nil {
+		return s
+	}
+	helper(root, strconv.Itoa(root.Val), &s)
+	return s
+}
+
+func helper(node *TreeNode, path string, s *[]string) {
+	if node.Left == nil && node.Right == nil {
+		*s = append(*s, path)
+	}
+	if node.Left != nil {
+		helper(node.Left, path+"->"+strconv.Itoa(node.Left.Val), s)
+	}
+	if node.Right != nil {
+		helper(node.Right, path+"->"+strconv.Itoa(node.Right.Val), s)
+	}
+
+}

268. Missing Number.go

@@ -0,0 +1,12 @@
+package main
+
+//NB
+func missingNumber(nums []int) int {
+	total := 0
+	for _, v := range nums {
+		total += v
+	}
+	l := len(nums)
+	sum := l * (l + 1) / 2
+	return sum - total
+}