1 Description #
source: https://leetcode.com/problems/reverse-bits/
Reverse bits of a given 32 bits unsigned integer.
Note:
- Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned.
- In Java, the compiler represents the signed integers using 2’s complement notation. Therefore, in Example 2 above, the input represents the signed integer -3 and the output represents the signed integer
-1073741825.
Example 1:
Input: n = 00000010100101000001111010011100
Output: 964176192 (00111001011110000010100101000000)
Explanation: The input binary string 00000010100101000001111010011100 represents the unsigned integer 43261596, so return 964176192 which its binary representation is 00111001011110000010100101000000.
Example 2:
Input: n = 11111111111111111111111111111101
Output: 3221225471 (10111111111111111111111111111111)
Explanation: The input binary string 11111111111111111111111111111101 represents the unsigned integer 4294967293, so return 3221225471 which its binary representation is 10111111111111111111111111111111.
Constraints:
- The input must be a binary string of length
32
Follow up: If this function is called many times, how would you optimize it?
2 Solution #
#include <bitset>
#include <sstream>
class Solution {
public:
uint32_t reverseBits(uint32_t n) {
std::string bin_str = std::bitset<32>(n).to_string();
std::stringstream ss;
for(int i = bin_str.size() -1 ; i >= 0; i--){
ss << bin_str[i];
}
std::bitset<32> result{ss.str()};
return result.to_ulong();
}
};