摘要：
Given a string containing only digits, restore it by returning all possible valid IP address combinations.For example:Given"25525511135",return["255.2... 阅读全文
摘要：
GivennumRows, generate the firstnumRowsof Pascal's triangle.For example, givennumRows= 5,Return[ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1]... 阅读全文
摘要：
PermutationsGiven a collection of numbers, return all possible permutations.For example,[1,2,3]have the following permutations:[1,2,3],[1,3,2],[2,1,3]... 阅读全文