Create 0513-find-bottom-left-tree-value.js

Author: aadil42

javascript/0513-find-bottom-left-tree-value.js

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+/**
+ * PreOrder Traversal
+ * Time O(n) | Space O(n) (because of the call stack space is O(n). If the tree has only left children then it's kind of  like a linkedList)
+ * https://leetcode.com/problems/find-bottom-left-tree-value/
+ * 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)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+var findBottomLeftValue = function(root) {
+    
+    let leftVal = 0;
+    let deepestLevel = -Infinity;
+
+    const dfs = (node, level) =>  {
+        if(!node.left && !node.right) {
+            if(level > deepestLevel) {
+                leftVal = node.val;
+                deepestLevel = level;
+            }       
+            return;
+        }
+
+        node.left &&  dfs(node.left, level+1);
+        node.right && dfs(node.right, level+1);
+    }
+
+    dfs(root, 0);
+    return leftVal;
+};