Question
Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).
For example, the 32-bit integer ’11' has binary representation 00000000000000000000000000001011, so the function should return 3.
解说
这道题的意思是统计32位整数二进制格式下的‘1’的个数。
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Solution
rig继续阅读 »
231. Power of Two
Question
Given an integer, write a function to determine if it is a power of two.
Solution
Approach #1 (count the number of 1) [Accepted]
Algorithm
Integer is a power of two means only one bit of n is '1', for example, 100 is 2^2=4 while 110 is 2^2+2^1=6.继续阅读 »
Question
Given an array of integers, return indices of the two numbers such that they add up to a specific target.
You may assume that each input would have exactly one solution.
Example:
Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].
UPDATE (2016/2/13):
The return forma继续阅读 »
Question
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.
After removing the second node from the end, the linked list becomes 1->2->3->5.
Note:
Given n will always be valid.
Try to do this in one pass.
解说
这道题的意思是，如何反向删继续阅读 »