Create 0106-construct-binary-tree-from-inorder-and-postorder-traversal.js

Author: aadil42

Diff for: javascript/0106-construct-binary-tree-from-inorder-and-postorder-traversal.js

@@ -0,0 +1,47 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * Recursion | Tree
+ * Time O(n) | Space O(n)
+ * https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/
+ * @param {number[]} inorder
+ * @param {number[]} postorder
+ * @return {TreeNode}
+ */
+var buildTree = function(inorder, postorder) {
+    
+
+    let globleIdx = inorder.length - 1;
+
+    const dfs = (start, end) => {
+        if(start === end) {
+            globleIdx--;
+            return new TreeNode(inorder[start]);
+        }
+
+        if(start > end) return null;
+
+        let i = start;
+
+        while(i < end + 1){
+            if(inorder[i] === postorder[globleIdx]) break;
+            i++;
+        }
+
+        globleIdx--;
+        const currRoot = new TreeNode(inorder[i]);
+
+        currRoot.right = dfs(i+1, end);
+        currRoot.left = dfs(start, i - 1);
+
+        return currRoot;
+    }
+
+    return dfs(0, globleIdx);
+};