Given a n-ary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.For example, given a 3-ary tree: We should return its max depth, which is 3. Solution:""" # Definition for a Node. class Node(object):def __init__(self, val, children):self.val = valself.children = children """class Solution(object):# DFSdef ...
原题地址：https://oj.leetcode.com/problems/largest-rectangle-in-histogram/题意：Given n non-negative integers representing the histogram‘s bar height where the width of each bar is 1, find the area of largest rectangle in the histogram.Above is a histogram where width of each bar is 1, given height = [2,1,5,6,2,3]. The largest rectangle is shown in the shaded area, which has area = 10 unit. For e...
原题地址：https://oj.leetcode.com/problems/find-minimum-in-rotated-sorted-array/解题思路：话说leetcode上面的二分查找题目真的不少啊。下图是这道题的数组的两种情况，分别去处理就可以了。 class Solution:# @param num, a list of integer# @return an integerdef findMin(self, num):L = 0; R = len(num)-1while L < R and num[L] > num[R]:M = (L+R)/2if num[M] < num[R]:R = Melse:L = M+1return num[L] 原文：http://w...
LeetCode 0700. Search in a Binary Search Tree二叉搜索树中的搜索【Easy】【Python】【二叉树】ProblemLeetCodeGiven the root node of a binary search tree (BST) and a value. You need to find the node in the BST that the node‘s value equals the given value. Return the subtree rooted with that node. If such node doesn‘t exist, you should return NULL.For example,Given the tree:4/ 2 7/ 1 3A...
题目来源： https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/ 题意分析： 和上题类似，给定array，代表第i天物品i的价格。如果可以交易无数次（手上有物品不能买），问最高利润。 题目思路： 记录当前最小值，如果遇到array[i] < min，那么加上当前的最大值；更新min。 代码（python）：class Solution(object):def maxProfit(self, prices):""":type prices: List[int]:rtype: int"""if len(prices)...
【python】Leetcode每日一题-删除排序链表中的重复元素【题目描述】给你一个链表的头节点 head ，旋转链表，将链表每个节点向右移动 k 个位置。示例1：输入：head = [1,2,3,4,5], k = 2 输出：[4,5,1,2,3] 示例2：输入：head = [0,1,2], k = 4 输出：[2,0,1] 提示：链表中节点的数目在范围 [0, 500] 内 -100 <= Node.val <= 100 0 <= k <= 2 * 10^9 【分析】思路由于 $ 0 \le k \le 2 * 10^9$ ，k较大，因此需要先求出链表总长度，...
Climbing StairsYou are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?python code：class Solution: # @param {integer} n # @return {integer} def climbStairs(self, n): if n<=0: #illegal input return 0 else: if...
Problem: Given an array and a value, remove all instances of that value in place and return the new length. The order of elements can be changed. It doesn‘t matter what you leave beyond the new length.Solution:和26题一样，就是判断条件不一样而已。题目大意：给一个数组，要求返回删除所有指定元素的数组。好鸡冻，第一次全部通过，没有一个错误（虽然题目比较简单）。。。。。。贴图留念：Java源代码（248ms）：...
LeetCode 面试题03. 数组中重复的数字【剑指Offer】【Easy】【Python】【数组】【哈希表】【排序】问题力扣找出数组中重复的数字。在一个长度为 n 的数组 nums 里的所有数字都在 0～n-1 的范围内。数组中某些数字是重复的，但不知道有几个数字重复了，也不知道每个数字重复了几次。请找出数组中任意一个重复的数字。示例 1：输入： [2, 3, 1, 0, 2, 5, 3] 输出：2 或 3 限制：2 <= n <= 100000思路解法一哈希表遍历数组，未出现过的...
最小栈 设计一个支持 push，pop，top 操作，并能在常数时间内检索到最小元素的栈。push(x)?-- 将元素 x 推入栈中。pop()?-- 删除栈顶的元素。top()?-- 获取栈顶元素。getMin() -- 检索栈中的最小元素。Python语言：使用辅助栈记录小的元素class MinStack:def __init__(self):"""initialize your data structure here."""self.stack=[]self.minstack=[]self.length = 0def push(self, x: int) -> None:self.stack.append(x)if se...
看似简单，实际上想了挺久的1）内置api方法class Solution:def merge(self, nums1: List[int], m: int, nums2: List[int], n: int) -> None:"""Do not return anything, modify nums1 in-place instead."""while nums1 and nums1[-1] == 0:if len(nums1) == m:breakdel nums1[-1]nums1 += nums2nums1.sort()2）双指针，哪个小输入哪个，再替换Nums1temp = []p1 = 0p2 = 0while(p1 < m and p2 < n):if (nums1[p1] <= nums2[p2]):tem...
题目：Given an index k, return the kth row of the Pascal‘s triangle.For example, given k = 3,Return [1,3,3,1].Note:Could you optimize your algorithm to use only O(k) extra space? 代码：oj测试通过 Runtime: 48 ms 1class Solution:2# @return a list of integers 3def getRow(self, rowIndex):4if rowIndex == 0:5return [1]6if rowIndex == 1:7return [1,1]8 pascal = [1,1]9for i in range(1,rowIndex): 1...
问题描述： Given an integer n, return the number of trailing zeroes in n!. Example 1: Input: 3 Output: 0 Explanation: 3! = 6, no trailing zero. Example 2: Input: 5 Output: 1 Explanation: 5! = 120, one trailing zero. Note: Your solution should be in logarithmic time complexity. 思路：在n!中，若想在结果的结尾产生0，只能是5乘以双数、或者某个乘数结尾为0，如10，但10可视为5*2，20可以视为5*4.综上要想找n!...
Word Break Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.For example, givens = "leetcode",dict = ["leet", "code"].Return true because "leetcode" can be segmented as "leet code". python code：class Solution: # @param s, a string # @param wordDict, a set<string> # @return a boolean def word...
Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2.Your algorithm should run in O(n) time and uses constant space.这题用的是count sort 的方法。首先我们来复习一下count sort已知一个正整数还未排列数列。 先遍历一遍得到最大值，建一个counter数组。再将counter里面的数依次赋值到原来的数组当中去。代码如下def counts(A):maxval...