199:二叉树的右视图

src/main/java/leetcode/editor/cn/BinaryTreeRightSideView.java

@@ -0,0 +1,100 @@
+//给定一个二叉树的 根节点 root，想象自己站在它的右侧，按照从顶部到底部的顺序，返回从右侧所能看到的节点值。 
+//
+// 
+//
+// 示例 1: 
+//
+// 
+//
+// 
+//输入: [1,2,3,null,5,null,4]
+//输出: [1,3,4]
+// 
+//
+// 示例 2: 
+//
+// 
+//输入: [1,null,3]
+//输出: [1,3]
+// 
+//
+// 示例 3: 
+//
+// 
+//输入: []
+//输出: []
+// 
+//
+// 
+//
+// 提示: 
+//
+// 
+// 二叉树的节点个数的范围是 [0,100] 
+// -100 <= Node.val <= 100 
+// 
+// Related Topics 树 深度优先搜索 广度优先搜索 二叉树 
+// 👍 502 👎 0
+
+package leetcode.editor.cn;
+
+import com.code.leet.entiy.TreeNode;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+//199:二叉树的右视图
+public class BinaryTreeRightSideView {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new BinaryTreeRightSideView().new Solution();
+    }
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+
+    /**
+     * Definition for a binary tree node.
+     * public class TreeNode {
+     * int val;
+     * TreeNode left;
+     * TreeNode right;
+     * TreeNode() {}
+     * TreeNode(int val) { this.val = val; }
+     * TreeNode(int val, TreeNode left, TreeNode right) {
+     * this.val = val;
+     * this.left = left;
+     * this.right = right;
+     * }
+     * }
+     */
+    class Solution {
+        public List<Integer> rightSideView(TreeNode root) {
+            List<Integer> list = new ArrayList<>();
+            if (root == null) {
+                return list;
+            }
+            Queue<TreeNode> queue = new LinkedList<>();
+            queue.offer(root);
+            while (!queue.isEmpty()) {
+                int size = queue.size();
+                for (int i = 1; i <= size; i++) {
+                    TreeNode node = queue.poll();
+                    if (node.left != null) {
+                        queue.offer(node.left);
+                    }
+                    if (node.right != null) {
+                        queue.offer(node.right);
+                    }
+                    if (i == size) {
+                        list.add(node.val);
+                    }
+                }
+            }
+            return list;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

src/main/java/leetcode/editor/cn/BinaryTreeRightSideView.md

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+<p>给定一个二叉树的 <strong>根节点</strong> <code>root</code>，想象自己站在它的右侧，按照从顶部到底部的顺序，返回从右侧所能看到的节点值。</p>
+
+<p> </p>
+
+<p><strong>示例 1:</strong></p>
+
+<p><img src="https://assets.leetcode.com/uploads/2021/02/14/tree.jpg" style="width: 270px; " /></p>
+
+<pre>
+<strong>输入:</strong> [1,2,3,null,5,null,4]
+<strong>输出:</strong> [1,3,4]
+</pre>
+
+<p><strong>示例 2:</strong></p>
+
+<pre>
+<strong>输入:</strong> [1,null,3]
+<strong>输出:</strong> [1,3]
+</pre>
+
+<p><strong>示例 3:</strong></p>
+
+<pre>
+<strong>输入:</strong> []
+<strong>输出:</strong> []
+</pre>
+
+<p> </p>
+
+<p><strong>提示:</strong></p>
+
+<ul>
+	<li>二叉树的节点个数的范围是 <code>[0,100]</code></li>
+	<li><meta charset="UTF-8" /><code>-100 <= Node.val <= 100</code> </li>
+</ul>
+<div><div>Related Topics</div><div><li>树</li><li>深度优先搜索</li><li>广度优先搜索</li><li>二叉树</li></div></div>\n<div><li>👍 502</li><li>👎 0</li></div>