Count the number of segments in a string, where a segment is defined to be a contiguous sequence of non-space characters. Please note that the string ...

Given a non-empty array of integers, return the third maximum number in this array. If it does not exist, return the maximum number. The time complexi ...

Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two’s complement method is used. Note All letters in hexadeci ...

Find the sum of all left leaves in a given binary tree. Example12345 3 / \9 20 / \ 15 7 There are two left leaves in the binary tree, with valu ...

Given two strings s and t which consist of only lowercase letters. String t is generated by random shuffling string s and then add one more letter at ...

Write a function that takes a string as input and reverse only the vowels of a string. ExampleNo.1Input: “hello” Output: “holle” No.2Input: “leetcode” ...

引入表示实例状态的角色，在保存和恢复实例时有效地防止对象的封装性遭到破坏。 示例一个收集水果和获取金钱数的掷骰子游戏，游戏规则很简单，具体如下。 游戏是自动进行的 游戏的主人公通过掷骰子来决定下一个状态 当骰子点数为1的时候，主人公的金钱会增加 当骰子点数为2的时候，主人公的金钱会减少 当骰子点数 ...

A Fenwick tree or binary indexed tree is a data structure that can efficiently update elements and calculate prefix sums in a table of numbers. 1D123 ...

A segment tree also known as a statistic tree is a tree data structure used for storing information about intervals, or segments. It allows querying w ...

A trie, also called digital tree, radix tree or prefix tree, is a kind of search tree—an ordered tree data structure used to store a dynamic set or as ...