Add solutions for BS tasks 94 and 450

leetcode/binary_trees/450_delete_from_binary_tree/main.go

@@ -0,0 +1,59 @@
+package main
+
+// Given a root node reference of a BST and a key, delete the node with the given key in the BST.
+// Return the root node reference (possibly updated) of the BST.
+//
+// Basically, the deletion can be divided into two stages:
+//
+// Search for a node to remove.
+// If the node is found, delete the node.
+
+// Constraints:
+//
+// The number of nodes in the tree is in the range [0, 104].
+// -105 <= Node.val <= 105
+// Each node has a unique value.
+// root is a valid binary search tree.
+// -105 <= key <= 105
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func findMin(subTreeRoot *TreeNode) *TreeNode {
+	for (subTreeRoot != nil) && (subTreeRoot.Left != nil) {
+		subTreeRoot = subTreeRoot.Left
+	}
+	return subTreeRoot
+}
+
+func deleteNode(root *TreeNode, key int) *TreeNode {
+	if root == nil {
+		return nil
+	}
+
+	if key < root.Val {
+		root.Left = deleteNode(root.Left, key)
+	} else if key > root.Val {
+		root.Right = deleteNode(root.Right, key)
+	} else {
+		if (root.Right == nil) && (root.Left == nil) {
+			root = nil
+			return root
+		} else if (root.Right != nil) && (root.Left == nil) {
+			root = root.Right
+			return root
+		} else if (root.Left != nil) && (root.Right == nil) {
+			root = root.Left
+			return root
+		} else if (root.Left != nil) && (root.Right != nil) {
+			minSubTreeNode := findMin(root.Right)
+			deleteNode(root.Right, minSubTreeNode.Val)
+			root.Val = minSubTreeNode.Val
+			return root
+		}
+	}
+	return root
+}

leetcode/binary_trees/94_binary_tree_inorder_traversal/main.go

@@ -0,0 +1,35 @@
+package main
+
+import "fmt"
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func traverse(root *TreeNode, res *[]int) {
+	if root == nil {
+		return
+	}
+	traverse(root.Left, res)
+	*res = append(*res, root.Val)
+	traverse(root.Right, res)
+}
+func inorderTraversal(root *TreeNode) []int {
+	var result []int
+	traverse(root, &result)
+	return result
+}
+
+func main() {
+	n10 := TreeNode{Val: 2}
+	n9 := TreeNode{Val: 5}
+	n8 := TreeNode{Val: 7}
+	n7 := TreeNode{Val: 6, Left: &n9, Right: &n8}
+	n6 := TreeNode{Val: 3, Left: &n10}
+	n5 := TreeNode{Val: 4, Left: &n6, Right: &n7}
+
+	res := inorderTraversal(&n5)
+	fmt.Print(res)
+}

neetcode/binary_trees/DFS/main.go

@@ -0,0 +1,78 @@
+package main
+
+import "fmt"
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func inorder(root *TreeNode) {
+	if root == nil {
+		return
+	}
+	inorder(root.Left)
+	fmt.Print(root.Val)
+	inorder(root.Right)
+}
+
+func preorder(root *TreeNode) {
+	if root == nil {
+		return
+	}
+	fmt.Print(root.Val)
+	preorder(root.Left)
+	preorder(root.Right)
+}
+
+func postorder(root *TreeNode) {
+	if root == nil {
+		return
+	}
+	postorder(root.Left)
+	postorder(root.Right)
+	fmt.Print(root.Val)
+}
+
+func reverserOrder(root *TreeNode) {
+  if root == nil {
+    return
+  }
+  reverserOrder(root.Right)
+  fmt.Print(root.Val)
+  reverserOrder(root.Left)
+}
+
+func traverse(root *TreeNode, res *[]int){
+    if root == nil {
+        return
+    }
+    traverse(root.Left, res)
+    *res = append(*res, root.Val)
+    traverse(root.Right, res)
+}
+func inorderTraversal(root *TreeNode) []int {
+    var result []int
+    traverse(root, &result)
+    return result
+}
+
+func main() {
+	n10 := TreeNode{Val: 2}
+	n9 := TreeNode{Val: 5}
+	n8 := TreeNode{Val: 7}
+	n7 := TreeNode{Val: 6, Left: &n9, Right: &n8}
+	n6 := TreeNode{Val: 3, Left: &n10}
+	n5 := TreeNode{Val: 4, Left: &n6, Right: &n7}
+
+	// inorder(&n5)
+	// fmt.Println()
+	// preorder(&n5)
+	// fmt.Println()
+	// postorder(&n5)
+	// fmt.Println()
+	// reverserOrder(&n5)
+  res := inorderTraversal(&n5)
+  fmt.Print(res)
+}