Binary Tree Right Side View

Author: w2xi

README.md

@@ -53,6 +53,7 @@
 |155|[最小栈](https://leetcode.cn/problems/min-stack/)|[JavaScript](./algorithms/min-stack.js)|Easy|
 |160|[相交链表](https://leetcode.cn/problems/intersection-of-two-linked-lists/)|[JavaScript](./algorithms/intersection-of-two-linked-lists.js)|Easy|
 |189|[轮转数组](https://leetcode-cn.com/problems/rotate-array/)|[JavaScript](./algorithms/rotate-array.js)|Medium|
+|199|[二叉树的右视图](https://leetcode.cn/problems/binary-tree-right-side-view/)|[JavaScript](./algorithms/binary-tree-right-side-view.js)|Medium|
 |203|[移除链表元素](https://leetcode.cn/problems/remove-linked-list-elements/)|[JavaScript](./algorithms/remove-linked-list-elements.js)|Easy|
 |206|[反转链表](https://leetcode-cn.com/problems/reverse-linked-list/)|[JavaScript](./algorithms/reverse-linked-list.js)|Easy|
 |222|[完全二叉树的节点个数](https://leetcode.cn/problems/count-complete-tree-nodes/)|[](JavaScript)|Medium|

algorithms/binary-tree-right-side-view.js

@@ -0,0 +1,37 @@
+/**
+ * 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 rightSideView = function (root) {
+  // 思路：
+  // 层序遍历的时候，判断是否遍历到单层的最后面的元素
+  // 如果是，就放进result数组中，随后返回result就可以了
+
+  const result = [];
+  const queue = [];
+  queue.push(root);
+
+  if (!root) return [];
+
+  while (queue.length > 0) {
+    let size = queue.length;
+
+    while (size--) {
+      const node = queue.shift();
+
+      size === 0 && result.push(node.val);
+      node.left && queue.push(node.left);
+      node.right && queue.push(node.right);
+    }
+  }
+
+  return result;
+};