好好学习 天天向上

摘要： Binary Tree Level Order Traversal IIGiven a binary tree, return thebottom-up level ordertraversal of its nodes' values. (ie, from left to right, level... 阅读全文

摘要： Implement Queue by Two StacksAs the title described, you should only use two stacks to implement a queue's actions.The queue should support push(eleme... 阅读全文

摘要： Roman to IntegerGiven a roman numeral, convert it to an integer.The answer is guaranteed to be within the range from 1 to 3999.ExampleIV -> 4XII -> 12... 阅读全文

摘要： Digit CountsCount the number of k's between 0 and n. k can be 0 - 9.Exampleif n=12, k=1 in [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12], we have FIVE 1'... 阅读全文

摘要： AnagramsGiven an array of strings, return all groups of strings that are anagrams.ExampleGiven ["lint", "intl", "inlt", "code"], return ["lint", "inlt... 阅读全文

摘要： k SumGiven n distinct positive integers, integer k (k <= n) and a number target.Find k numbers where sum is target. Calculate how many solutions there... 阅读全文

摘要： Maximum Subarray DifferenceGiven an array with integers.Find two non-overlapping subarrays A and B, which |SUM(A) - SUM(B)| is the largest.Return the ... 阅读全文

摘要： Delete DigitsGiven string A representative a positive integer which has N digits, remove any k digits of the number, the remaining digits are arranged... 阅读全文

摘要： Maximum Subarray IIGiven an array of integers, find two non-overlapping subarrays which have the largest sum. The number in each subarray should be co... 阅读全文

摘要： Best Time to Buy and Sell StockSay you have an array for which theithelement is the price of a given stock on dayi.If you were only permitted to compl... 阅读全文