{"id":11114,"date":"2020-01-05T20:53:22","date_gmt":"2020-01-05T20:53:22","guid":{"rendered":"http:\/\/www.softwareeverydayblog.com\/?p=11114"},"modified":"2020-01-05T20:53:46","modified_gmt":"2020-01-05T20:53:46","slug":"programming-problem-n-ary-tree-level-order-traversal","status":"publish","type":"post","link":"https:\/\/www.softwareeverydayblog.com\/?p=11114","title":{"rendered":"[Programming Problem] N-ary Tree Level Order Traversal"},"content":{"rendered":"<p>Given an n-ary tree, return the level order traversal of its nodes&#8217; values.<\/p>\n<p><a href=\"https:\/\/www.softwareeverydayblog.com\/wp-content\/uploads\/2020\/01\/nary-tree-lc-e1578257413972.png\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.softwareeverydayblog.com\/wp-content\/uploads\/2020\/01\/nary-tree-lc-e1578257413972.png\" alt=\"\" width=\"500\" height=\"276\" class=\"alignnone size-full wp-image-11115\" \/><\/a><\/p>\n<p>[<a href=\"https:\/\/leetcode.com\/problems\/n-ary-tree-level-order-traversal\/\" rel=\"noopener noreferrer\" target=\"_blank\">Problem Link<\/a>]<\/p>\n<p>Pretty straightforward BFS traversal logic. Here are some small gotcha&#8217;s:<\/p>\n<ul>\n<li>Add condition for empty\/undefined input.<\/li>\n<li>When you return the list of lists, the expectation is to return just values and not the Node object. Notice the last line (ret.map(..)) is doing just that.<\/li>\n<\/ul>\n<pre lang=\"javascript\">\r\n\/**\r\n * \/\/ Definition for a Node.\r\n * function Node(val,children) {\r\n *    this.val = val;\r\n *    this.children = children;\r\n * };\r\n *\/\r\n\/**\r\n * @param {Node} root\r\n * @return {number[][]}\r\n *\/\r\nvar levelOrder = function(root) {\r\n    if ( !root || root.length === 0) return [];\r\n    let ret = [[root]];\r\n    let currLevel = 0;\r\n    while (true) {\r\n        let nextLevel = [];\r\n        ret[currLevel].forEach((item) => item.children.forEach((child) => nextLevel.push(child))); \r\n        if ( nextLevel.length === 0 ) break;\r\n        ret.push(nextLevel);\r\n        currLevel++;\r\n    }    \r\n    return ret.map((arr) => arr.map((item) => item.val))\r\n};\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Given an n-ary tree, return the level order traversal of its nodes&#8217; values. [Problem Link] Pretty straightforward BFS traversal logic. Here are some small gotcha&#8217;s: Add condition for empty\/undefined input. When you return the list of lists, the expectation is to return just values and not the Node object. Notice the last line (ret.map(..)) is [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-11114","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=\/wp\/v2\/posts\/11114","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=11114"}],"version-history":[{"count":2,"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=\/wp\/v2\/posts\/11114\/revisions"}],"predecessor-version":[{"id":11117,"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=\/wp\/v2\/posts\/11114\/revisions\/11117"}],"wp:attachment":[{"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11114"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11114"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.softwareeverydayblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11114"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}