摘要： Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the arr 阅读全文

摘要： Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be 阅读全文

摘要： Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element. For exam 阅读全文

摘要： Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can f 阅读全文