标签：push tput strong color -- info logs targe block
多叉树的先序遍历。题意很直观，就是给一个多叉树，请你输出先序遍历的结果。跟二叉树的先序遍历一样，还是两种做法，BFS和DFS。两种做法的时间复杂度是O(n)，空间复杂度是O(h)。例子，
Input: root = [1,null,3,2,4,null,5,6]
Output: [1,3,5,6,2,4]
BFS
1 /** 2 * @param {Node} root 3 * @return {number[]} 4 */ 5 var preorder = function (root) { 6 let res = []; 7 if (root === null) return res; 8 let stack = [root]; 9 while (stack.length) { 10 let cur = stack.pop(); 11 let size = cur.children.length; 12 for (let i = size - 1; i >= 0; i--) { 13 stack.push(cur.children[i]); 14 } 15 res.push(cur.val); 16 } 17 return res; 18 };
DFS
1 /** 2 * @param {Node} root 3 * @return {number} 4 */ 5 var preorder = function (root) { 6 let res = []; 7 if (root === null) return res; 8 helper(res, root); 9 return res; 10 }; 11 12 var helper = function (res, root) { 13 if (root === null) return; 14 res.push(root.val); 15 for (let child of root.children) { 16 helper(res, child); 17 } 18 }
[LeetCode] 589. N-ary Tree Preorder Traversal
标签：push tput strong color -- info logs targe block
原文地址：https://www.cnblogs.com/aaronliu1991/p/12194783.html
