问题描述 Given a binary tree, find the left most element in the last row of the tree. Example 1: Input: 2 / \ 1 3 Output: 1 Example 2: Input: 1 / \ 2 3 / / \ 4 5 6 / 7 Output: 7 Note: You may assume the tree is not NULL. 算法分析: 逐层遍历二叉树是很经典的算法,常规的逐层遍历二叉树是使…

问题描述 You need to find the largest element in each row of a Binary Tree. Example: Input: 1 / \ 2 3 / \ \ 5 3 9 Output: [1, 3, 9] 算法分析 使用两个队列,逐层遍历二叉树的各个节点,每个队列中的节点都是同一层的节点,在遍历一层时,找出该层最大的节点值加入ArrayList中. Java算法实现: /** * Definition for a binary tree node…

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times. You may assume that the array is non-empty and the majority element always exist in the array. 题解:设置两个变量,一个是current,初始化为A[0…

395. Longest Substring with At least K Repeating Characters Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times. Example 1: Input: s = "aaabb&qu…

394. Decode String Given an encoded string, return it's decoded string. The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k times. Note that k is guaranteed to be a positive integer…

393. UTF-8 Validation A character in UTF8 can be from 1 to 4 bytes long, subjected to the following rules: For 1-byte character, the first bit is a 0, followed by its unicode code. For n-bytes character, the first n-bits are all one's, the n+1 bit is…

392. Is Subsequence Given a string s and a string t, check if s is subsequence of t. You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) string, and s is a short string (<=100…

#391. Perfect Rectangle Given N axis-aligned rectangles where N > 0, determine if they all together form an exact cover of a rectangular region. Each rectangle is represented as a bottom-left point and a top-right point. For example, a unit square is…

# 390. Elimination Game There is a list of sorted integers from 1 to n. Starting from left to right, remove the first number and every other number afterward until you reach the end of the list. Repeat the previous step again, but this time from righ…

乘风破浪:LeetCode真题_034_Find First and Last Position of Element in Sorted Array 一.前言 这次我们还是要改造二分搜索,但是想法却有一点不一样. 二.Find First and Last Position of Element in Sorted Array 2.1 问题 2.2 分析与解决 查找问题,时间复杂度要求对数级别的,我们自然的想到了二分查找,和上一题一样,需求都是有点不一样的,这次是有重复的数字,找出某一特定的重…