07 2014 档案
摘要：题目：Given a collection of integers that might contain duplicates, S, return all possible subsets.Note:Elements in a subset must be in non-descending o...
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摘要：题目：Given a set of distinct integers, S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must n...
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摘要：题目：Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the tele...
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摘要：题目：Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.For example:Given the below binary tree and ...
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摘要：题目：Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given su...
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摘要：题目：Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as a binary tree in which the d...
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摘要：题目：Given an array where elements are sorted in ascending order, convert it to a height balanced BST.题解：先复习下什么是二叉搜索树（引自Wikipedia）：二叉查找树（Binary Search ...
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摘要：题目：Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the neares...
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摘要：题目：Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthes...
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摘要：题目：Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric: 1 /...
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摘要：题目：Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identica...
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摘要：题目：Given a binary tree, return the postorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [3...
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摘要：题目：Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,...
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摘要：题目：Given a binary tree, return the inorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,3...
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摘要：题目：Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.For example,If n = 4 and k = 2, a solution is:[ [2,4], ...
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摘要：题目：There are N children standing in a line. Each child is assigned a rating value. You are giving candies to these children subjected to the followin...
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摘要：题目：Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after rain...
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摘要：题目：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 com...
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摘要：题目：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 com...
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摘要：题目：Say you have an array for which the ith element is the price of a given stock on day i.If you were only permitted to complete at most one transact...
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摘要：题目： Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array [−2,1,−3,4,−1...
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摘要：题目：Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word.Return all suc...
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摘要：题目：Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.F...
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摘要：题目：Given an array of strings, return all groups of strings that are anagrams.Note: All inputs will be in lower-case.题解：这道题看所给的字符串数组里面有多少个是同一个变形词变的。这道...
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摘要：题目：Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.OJ's undirected graph serialization:Nodes are label...
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摘要：题目：Given two sorted integer arrays A and B, merge B into A as one sorted array.Note:You may assume that A has enough space (size that is greater or e...
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摘要：题目：Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).For example,S = "ADOBE...
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摘要：题目：You are given a string, S, and a list of words, L, that are all of the same length. Find all starting indices of substring(s) in S that is a conca...
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摘要：题目：Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).You may assume that the intervals were ini...
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摘要：题目：Given a collection of intervals, merge all overlapping intervals.For example,Given [1,3],[2,6],[8,10],[15,18],return [1,6],[8,10],[15,18].题解：这道题主要...
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摘要：题目：Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letter...
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摘要：题目：Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.If the last w...
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摘要：题目：Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your ma...
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摘要：题目：Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your ma...
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摘要：题目：Write a function to find the longest common prefix string amongst an array of strings.题解：解题思路是，先对整个String数组预处理一下，求一个最小长度（最长前缀肯定不能大于最小长度）。然后以第0个字符串...
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摘要：题目：Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order r...
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摘要：题目：Given an array and a value, remove all instances of that value in place and return the new length.The order of elements can be changed. It doesn't...
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摘要：题目：Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.Do not allocate extra space...
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摘要：题目：Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two e...
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摘要：题目：Divide two integers without using multiplication, division and mod operator.题解：这道题我自己没想出来。。。乘除取模都不让用。。那只有加减了。。。我参考的http://blog.csdn.net/perfect888...
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摘要：题目：Follow up for N-Queens problem.Now, instead outputting board configurations, return the total number of distinct solutions.题解：这道题跟NQueens的解法完全一样（具...
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摘要：题目：The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.Given an integer n, return a...
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摘要：题目：Implement pow(x, n).题解：pow(x,n)就是求x的n次方。x的N次方可以看做：x^n = x^(n/2)*x^(n/2)*x^(n%2)。所以利用递归求解，当n==1的时候，x^n=x。当然n是可以小于0的，2^(-3) = 1/(2^3)。按照上面那个规律就可以解决了...
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摘要：题目：Given an array of integers, every element appears three times except for one. Find that single one.Note:Your algorithm should have a linear runtim...
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摘要：题目：Given an array of integers, every element appears twice except for one. Find that single one.Note:Your algorithm should have a linear runtime comp...
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摘要：题目：Given an unsorted array of integers, find the length of the longest consecutive elements sequence.For example,Given [100, 4, 200, 1, 3, 2],The lon...
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摘要：题目：Given a 2D board containing 'X' and 'O', capture all regions surrounded by 'X'.A region is captured by flipping all 'O's into 'X's in that surroun...
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摘要：题目：Evaluate the value of an arithmetic expression in Reverse Polish Notation.Valid operators are +, -, *, /. Each operand may be an integer or anothe...
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摘要：String 字符串常量StringBuffer 字符串变量（线程安全）StringBuilder 字符串变量（非线程安全）简要的说， String 类型和 StringBuffer 类型的主要性能区别其实在于 String 是不可变的对象, 因此在每次对 String 类型进行改变的时候其实都等同...
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摘要：题目：Given an absolute path for a file (Unix-style), simplify it.For example,path = "/home/", => "/home"path = "/a/./b/../../c/", => "/c"Corner Cases:D...
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摘要：题目：Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.For "(()", the...
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摘要：题目：Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area.题解：这道题可以应用之前解过的Largetst Recta...
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摘要：题目：Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the ...
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摘要：题目：Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.The brackets must close in t...
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摘要：题目：Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.get(key) - Get ...
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摘要：题目：Sort a linked list in O(n log n) time using constant space complexity.题解：考虑到要求用O(nlogn)的时间复杂度和constant space complexity来sort list，自然而然想到了merge sor...
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摘要：题目：Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…You must do this in-place without altering the nodes' values.F...
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摘要：leetcode很多题目都是利用快慢指针来解决题目，下面具体讲解下快慢指针。概念： 快指针在每一步走的步长要比慢指针一步走的步长要多。快指针通常的步速是慢指针的2倍。在循环中的指针移动通常为：faster = faster.next.next, slower = slower.next.应用：1....
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摘要：题目：Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.题解：Merge k sorted linked list就是merge 2 sorted li...
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摘要：题目：Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.If the number of nodes is not a multiple of k the...
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摘要：题目:You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a sin...
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摘要：题目：A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.Return a deep c...
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摘要：题目：Given a list, rotate the list to the right by k places, where k is non-negative.For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2-...
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摘要：题目：Given a binary tree, flatten it to a linked list in-place.For example,Given 1 / \ 2 5 / \ \ 3 4 6The flatten...
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摘要：题目：Reverse a linked list from position m to n. Do it in-place and in one-pass.For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4,return 1->4->3->...
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摘要：题目：Sort a linked list using insertion sort.题解：Insertion Sort就是把一个一个元素往已排好序的list中插入的过程。初始时，sorted list是空，把一个元素插入sorted list中。然后，在每一次插入过程中，都是找到最合适位置进行插...
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摘要：题目：Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.You should preserve t...
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摘要：题目：Given a linked list, remove the nth node from the end of list and return its head.For example, Given linked list: 1->2->3->4->5, and n = 2. Af...
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摘要：题目：Given a linked list, return the node where the cycle begins. If there is no cycle, return null.Follow up:Can you solve it without using extra spac...
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摘要：题目：Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?题解：这道题连带着II是很经典的，在看CC150时候，纠结这个问题纠结了很久...
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摘要：题目：Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.For example,Given 1...
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摘要：题目：Given a sorted linked list, delete all duplicates such that each element appear only once.For example,Given 1->1->2, return 1->2.Given 1->1->2->3-...
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摘要：题目： Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 题解：...
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摘要：题目：Given a linked list, swap every two adjacent nodes and return its head.For example,Given 1->2->3->4, you should return the list as 2->1->4->3.http...
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摘要：题目：There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should ...
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摘要：题目：Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integ...
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摘要：题目：Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array w...
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摘要：题目： Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum...
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摘要：Hashtable:1. key和value都不许有null值2. 使用enumeration遍历3. 同步的，每次只有一个线程能够访问4. 在java中Hashtable是H大写，t小写，而HashMap是H大写，M大写HashMap:1. key和value可以有null值2. 使用itera...
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摘要：题目:Given an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the tw...
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摘要：题目：Follow up for "Search in Rotated Sorted Array":What if duplicates are allowed?Would this affect the run-time complexity? How and why?Write a funct...
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摘要：题目：Suppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).You are given a target ...
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摘要：题目：Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:Integers in each row are sorte...
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摘要：Reference: http://blog.csdn.net/lbyxiafei/article/details/9375735题目：Implement int sqrt(int x).Compute and return the square root of x.题解： 这道题很巧妙的运用了二...
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摘要：题目：Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the...
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摘要：Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in or...
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摘要：二分查找方法二分查找经常用来在有序的数列查找某个特定的位置。因此，应用二分查找法，这个数列必须包含以下特征：存储在数组中有序排列二分查找方法不适用于链表，因为链表方法需要遍历，应用二分查找法意义不大。一般情况下，我们默认数组是单调递增数列，且无重复元素。（有重复元素的题应该如何解决）二分查找方法递归...
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