# LeetCode 342. Power of Four

题目Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
Example 1:
12Input: 16Output: true
Example 2:
12Input: 5Ou
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题目Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
Example 1:
12Input: 16Output: true
Example 2:
12Input: 5Ou
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题目Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
Note: For the purpose of this problem,
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题目Design a HashSet without using any built-in hash table libraries.
To be specific, your design should include these functions:
add(value): Insert a
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题目Given a word, you need to judge whether the usage of capitals in it is right or not.
We define the usage of capitals in a word to be right when one
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题目You are climbing a stair case. It takes n steps to reach to the top.
Each time you can either climb 1 or 2 steps. In how many distinct ways can you
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题目Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, add spaces in s to construct a sentence where each word i
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题目Say you have an array for which the i^th 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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题目You are given a char array representing tasks CPU need to do. It contains capital letters A to Z where each letter represents a different task. Task
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题目Given inorder and postorder traversal of a tree, construct the binary tree.
Note:
You may assume that duplicates do not exist in the tree.
For examp
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题目Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
Example:
1234Input: 38Output: 2 Explanation: Th
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