leetcode_190题——Reverse Bits（bitset的使用）

Reverse Bits

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Question  Solution 

 

Reverse bits of a given 32 bits unsigned integer.

For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as00111001011110000010100101000000).

Follow up:
If this function is called many times, how would you optimize it?

Related problem: Reverse Integer

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

 

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  Bit Manipulation

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     这道题目的意思是将一个32位字节存储的一个数，在二进制上前后旋转，然后得到一个新的二进制数，再将二进制数转换成unsigned long型的数输出

所以这道题用C++做的话很简单，主要是考虑bitset的使用（初始化和使用函数to_ulong）

#include<iostream>

#include <bitset>

using namespace std;

typedef unsigned long uint32_t;





uint32_t reverseBits(uint32_t n) {

	uint32_t result;

	//unsigned long val=n;

	int val=n;

	bitset<32>bit_temp(val);



	for(int i=0;i<16;i++)

	{

		bool temp;

		temp=bit_temp[i];

		bit_temp[i]=bit_temp[31-i];

		bit_temp[31-i]=temp;

	}

	result=bit_temp.to_ulong();

	return result;

}



int main()

{

	//cout<<reverseBits(1)<<endl;

	

	unsigned long a=12;



	cout<<sizeof(unsigned long)<<endl;

	cout<<sizeof(int)<<endl;

	cout<<sizeof(long)<<endl;

	bitset<32> temp(a);



}