fix(checkpoint) add imports and functions needed

subjects/btreedeletenode/main.go

@@ -2,22 +2,59 @@ package main
 
 import (
 	"fmt"
+	"piscine"
 )
 
-type TreeNode struct {
-	Left, Right, Parent *TreeNode
-	Data                string
-}
-
 func main() {
-	root := &TreeNode{Data: "4"}
+	root := &piscine.TreeNode{Data: "4"}
 	BTreeInsertData(root, "1")
 	BTreeInsertData(root, "7")
 	BTreeInsertData(root, "5")
 	node := BTreeSearchItem(root, "4")
 	fmt.Println("Before delete:")
 	BTreeApplyInorder(root, fmt.Println)
-	root = BTreeDeleteNode(root, node)
+	root = piscine.BTreeDeleteNode(root, node)
 	fmt.Println("After delete:")
 	BTreeApplyInorder(root, fmt.Println)
 }
+
+func BTreeInsertData(root *piscine.TreeNode, data string) *piscine.TreeNode {
+	if root == nil {
+		return &piscine.TreeNode{Data: data}
+	}
+
+	if data < root.Data {
+		root.Left = BTreeInsertData(root.Left, data)
+		root.Left.Parent = root
+	} else {
+		root.Right = BTreeInsertData(root.Right, data)
+		root.Right.Parent = root
+	}
+
+	return root
+}
+
+func BTreeSearchItem(root *piscine.TreeNode, elem string) *piscine.TreeNode {
+	if root == nil {
+		return nil
+	}
+
+	if elem > root.Data {
+		return BTreeSearchItem(root.Right, elem)
+	} else if elem < root.Data {
+		return BTreeSearchItem(root.Left, elem)
+	} else if elem == root.Data {
+		return root
+	} else {
+		return root
+	}
+}
+
+func BTreeApplyInorder(root *piscine.TreeNode, f func(...interface{}) (int, error)) {
+	if root == nil {
+		return
+	}
+	BTreeApplyInorder(root.Left, f)
+	f(root.Data)
+	BTreeApplyInorder(root.Right, f)
+}

subjects/sortedlistmerge/main.go

@@ -5,14 +5,9 @@ import (
 	"piscine"
 )
 
-type NodeL struct {
-	Data interface{}
-	Next *NodeL
-}
-
-type List struct {
-	Head *NodeL
-	Tail *NodeL
+type NodeI struct {
+	Data int
+	Next *NodeI
 }
 
 func PrintList(l *piscine.NodeI) {