✨ [102] GETTING EASIER!

Author: enkr1

102/my_solution.js

@@ -0,0 +1,75 @@
+class TreeNode {
+  constructor(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[][]}
+ */
+const levelOrder = (root) => {
+  if (null === root) return [];
+
+  let list = [[root.val]], children = 2, visitedChildren = 0, nullChildren = 0, level = 1, queue = [root], levelVal = [];
+
+  while (queue.length > 0) {
+    let curr = queue.shift(), left = curr.left, right = curr.right;
+    console.log(`-> level:${level}, children:${children}, visitedChildren:${visitedChildren}, nullChildren:${nullChildren}, levelVal:${levelVal}`)
+    console.log(curr)
+    if (null !== left) {
+      queue.push(left);
+      visitedChildren++;
+      levelVal.push(left.val);
+    } else {
+      nullChildren++;
+    }
+
+    if (null !== right) {
+      queue.push(right);
+      visitedChildren++;
+      levelVal.push(right.val);
+    } else {
+      nullChildren++;
+    }
+
+    console.log(`--> level:${level}, children:${children}, visitedChildren:${visitedChildren}, nullChildren:${nullChildren}, levelVal:${levelVal}`)
+
+    if (children === (visitedChildren + nullChildren)) {
+
+      // if (undefined === list[level]) {
+      if (levelVal.length > 0) list[level] = levelVal;
+      // } else {
+      //   list[level] = list[level].concat(levelVal)
+      // }
+      levelVal = [];
+      children *= 2;
+      level++;
+      visitedChildren = 0;
+      nullChildren *= 2;
+    }
+  }
+
+  console.log(list);
+
+  return list;
+};
+
+// [1,2,null,3,null,4,null,5]
+let x =
+  // levelOrder(
+  //   new TreeNode()
+  // )
+  levelOrder(
+    new TreeNode(1,
+      new TreeNode(2,
+        new TreeNode(3,
+          new TreeNode(4,
+            new TreeNode(5)
+          )
+        )
+      )
+    )
+  )

102/solution.js

@@ -0,0 +1,48 @@
+/**
+ * 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[][]}
+ */
+const levelOrder = (root) => {
+  if (null === root) return [];
+
+  let list = [[root.val]], children = 2, visitedChildren = 0, nullChildren = 0, level = 1, queue = [root], levelVal = [];
+
+  while (queue.length > 0) {
+    let curr = queue.shift(), left = curr.left, right = curr.right;
+
+    if (null !== left) {
+      queue.push(left);
+      visitedChildren++;
+      levelVal.push(left.val);
+    } else {
+      nullChildren++;
+    }
+
+    if (null !== right) {
+      queue.push(right);
+      visitedChildren++;
+      levelVal.push(right.val);
+    } else {
+      nullChildren++;
+    }
+
+    if (children === (visitedChildren + nullChildren)) {
+      if (levelVal.length > 0) list[level] = levelVal;
+      levelVal = [];
+      level++;
+      children *= 2;
+      visitedChildren = 0;
+      nullChildren *= 2;
+    }
+  }
+
+  return list;
+};

README.md

@@ -37,6 +37,7 @@
 - [79. Word Search](./79/)
 - [83. Remove Duplicates from Sorted List](./83/)
 - [100. Same Tree](./100/)
+- [102. Binary Tree Level Order Traversal](./102/)
 - [104. Maximum Depth of Binary Tree](./104/)
 - [121. Best Time to Buy and Sell Stock](./121/)
 - [128. Longest Consecutive Sequence](./128/)
@@ -141,7 +142,7 @@ Batch create:
 NOTE: JS IS HERE
 -->
 ```ssh
-chapter=572 && mkdir ./$chapter && touch ./$chapter/my_solution.js && touch ./$chapter/solution.js && alias x="node ./$chapter/my_solution.js"
+chapter=102 && mkdir ./$chapter && touch ./$chapter/my_solution.js && touch ./$chapter/solution.js && alias x="node ./$chapter/my_solution.js"
 ```
 > then you can use `x` for quick debug.