09 2017 档案
摘要：最近在刷leetcode，发现很多题目的思路都很相似。其中，collections模块中的Counter()多次在习题中碰到，很有必要对该知识点总结一下，加深理解。 1.collections模块 collections模块自Python 2.4 版本之后，引入除了dict、list、set、tup
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摘要：Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assum
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摘要：Given an integer array with no duplicates. A maximum tree building on this array is defined as follow: Construct the maximum tree by the given array a
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摘要：Given the root of a tree, you are asked to find the most frequent subtree sum. The subtree sum of a node is defined as the sum of all the node values
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摘要：In English, we have a concept called root, which can be followed by some other words to form another longer word - let's call this word successor. For
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摘要：Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and r
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摘要：Given a binary tree, find the leftmost value in the last row of the tree. Example 1: Example 2: Note: You may assume the tree (i.e., the given root no
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摘要：You need to find the largest value in each row of a binary tree. Example:
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摘要：Suppose you have N integers from 1 to N. We define a beautiful arrangement as an array that is constructed by these N numbers successfully if one of t
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摘要：A sequence of number is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the
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摘要：Given a sorted array consisting of only integers where every element appears twice except for one element which appears once. Find this single element
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摘要：Given a binary tree, return the tilt of the whole tree. The tilt of a tree node is defined as the absolute difference between the sum of all left subt
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摘要：Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, with values 9 and 1
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摘要：Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number. The function
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摘要：Given a Binary Search Tree and a target number, return true if there exist two elements in the BST such that their sum is equal to the given target. E
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摘要：Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may comple
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摘要：Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a g
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摘要：Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the rans
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摘要：Given a table salary, such as the one below, that has m=male and f=female values. Swap all f and m values (i.e., change all f values to m and vice ver
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摘要：Given an array of 2n integers, your task is to group these integers into n pairs of integer, say (a1, b1), (a2, b2), ..., (an, bn) which makes sum of
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摘要：Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are n
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摘要：The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Given two integers x and y, calcul
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摘要：There is a table World A country is big if it has an area of bigger than 3 million square km or a population of more than 25 million. Write a SQL solu
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摘要：Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might
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摘要：Given a positive integer, return its corresponding column title as appear in an Excel sheet. For example:
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摘要：Given a column title as appear in an Excel sheet, return its corresponding column number. For example: 相关问题：http://www.cnblogs.com/yancea/p/7506456.ht
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摘要：Given two arrays, write a function to compute their intersection. Example:Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2]. Note: Each element i
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摘要：Given a non-empty integer array of size n, find the minimum number of moves required to make all array elements equal, where a move is incrementing n
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摘要：Initially, there is a Robot at position (0, 0). Given a sequence of its moves, judge if this robot makes a circle, which means it moves back to the or
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