solved: 106. Construct Binary Tree from Inorder and Postorder Traversal

Author: rajput-hemant

src/0101-0200/106 - Construct Binary Tree from Inorder and Postorder Traversal/construct_binary_tree_from_inorder_and_postorder_traversal.go

@@ -0,0 +1,35 @@
+package main
+
+// Definition for a binary tree node.
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func buildTree(inorder []int, postorder []int) *TreeNode {
+	mapInOrder := make(map[int]int)
+
+	for i, v := range inorder {
+		mapInOrder[v] = i
+	}
+
+	var helper func(int, int) *TreeNode
+	helper = func(left, right int) *TreeNode {
+		if left > right {
+			return nil
+		}
+
+		pop := postorder[len(postorder)-1]
+		postorder = postorder[:len(postorder)-1]
+
+		root := &TreeNode{Val: pop}
+		mid := mapInOrder[pop]
+		root.Right = helper(mid+1, right)
+		root.Left = helper(left, mid-1)
+
+		return root
+	}
+
+	return helper(0, len(inorder)-1)
+}