原创 leetCode:215. Kth Largest Element in an Array

Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not th

原创 leetcode:468. Validate IP Address

Write a function to check whether an input string is a valid IPv4 address or IPv6 address or neither. IPv4 addresses

原创 leetcode:44. Wildcard Matching

Implement wildcard pattern matching with support for '?' and '*'. '?' Matches any single character. '*' Matches any

原创 leetCode:493. Reverse Pairs

Given an array nums, we call (i, j) an important reverse pair if i < j and nums[i] > 2*nums[j]. You need to return

原创 leetcode:115. Distinct Subsequences

Given a string S and a string T, count the number of distinct subsequences of T in S. A subsequence of a string is a

原创 87. Scramble String

Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Bel

原创 leetcode:125. Valid Palindrome

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For e

原创 leetcode:72. Edit Distance

Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation

原创 leetcode:67. Add Binary

Given two binary strings, return their sum (also a binary string). For example,a = "11"b = "1" Return "100". 題意&解題思路

原创 leetcode:459. Repeated Substring Pattern

Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of t

原创 leetcode:49. Group Anagrams

Given an array of strings, group anagrams together. For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], 

原创 leetcode:338. Counting Bits

Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1’s in th

原创 leetcode:17. Letter Combinations of a Phone Number

Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to

原创 leetcode:413. Arithmetic Slices

A sequence of number is called arithmetic if it consists of at least three elements and if the difference between any t

原创 28. Implement strStr()

Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of hay