Author: darkcar88@gmail.com

Topological Sort

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Tree Traversal code implementation in Recursive and Iterative Ways

1. Description Recursive way is based on computer program, the function calling stack. While iterative way is programmer use stack to simulate it. 2. Solution

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LRU Cache – LeetCode 146

1. Description Design and Implement a data structure for LRU cache. It should support get and put. get(key) – Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.put(key, value) – Set or insert the value if the key is not already present. When the cache reached […]

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Base 7

1. Description Given an integer, return its base 7 string representation. 2. Example 3. Solution 4. Complexity Time: O(n) Space: O(1)

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Find the sum of the two elements of a given array which is equal to an given integer

1. Description Asked by Google. Given a list of numbers and a number k, return whether any two numbers from the list add up to k. 2. Example Given [10, 15, 3, 7] and k of 17, return true, since 10+7 is 17. 3. Solution – 3 ways to solve it.

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Shortest Unsorted Continuous Subarray

1. Description Given an integer array, you need to find one¬†continuous subarray¬†that if you only sort this subarray in ascending order, then the whole array will be sorted in ascending order, too. You need to find the shortest such subarray and output its length. Example 1: Input: [2, 6, 4, 8, 10, 9, 15] Output: 5 Explanation: […]

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Use Struts2 + Hibernate Implement CRM Application

Apache Struts is a free, open-source, MVC framework for creating elegant, modern Java Web applications. This post introduces an app implement by Struts + Hibernate.

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Best time to buy and sell stock – one time transaction

1. Description 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 transaction (i.e., buy one and sell one share of the stock), design an algorithm to find the maximum profit. Note that you cannot sell a stock […]

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Word Pattern

1. Description Give a pattern and a string, and check if the string follows the pattern. 2. Example 3. Solution 3.1 Wrong solution First, I was thinking, if I can use the AscII code to represent the pattern. For example: hello -> ‘a’, and hello -> ‘a’, world -> ‘b’, world->’b’. Use the data structure […]

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Google Initial Phone Screen with Recruiter

1. Questions What’s the best/worst running time of Merge Sort? O(nlogn), O(nlogn) What’s the best/worst running time of Quick Sort? O(n), O(n^2) What’s the worst running time for a look up in a HashTable? O(n) two reasons: if too many elements were hashed into the same key: looking inside this key may take O(n) time; […]

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