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199. 二叉树的右视图

给定一棵二叉树，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。

链接

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */

function rightSideView(root: TreeNode | null): number[] {
  const res: number[] = [];
  if (root === null) return res;
  const nodeQues: TreeNode[] = [root];
  while(nodeQues.length > 0) {
    const childs = nodeQues.splice(0);
    const clen = childs.length;
    res.push(childs[clen - 1].val)
    for(let i = 0; i < clen; i++) {
      const node = childs[i];
      if (node.left) nodeQues.push(node.left)
      if (node.right) nodeQues.push(node.right)
    }
  }
  return res
};