[Leetcode] Reverse Bits

Reverse Bits

Reverse bits of a given the unsigned integer.

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

Followup:
If This function is called many times, what would you optimize it?

Problem Solving Ideas:

Calculated by shifting. Here's the code:

Class Solution {public:    uint32_t reversebits (uint32_t N) {        uint32_t result=0;        int size = sizeof (uint32_t) *8;        for (int i=0; i<size; i++) {            result = result << 1;            result + = n%2;            n=n>>1;        }        return result;}    ;

Notice that if n is a very small number, there is no need to loop the size bit, if n is shifted to a position of 0, you can jump out of the loop. Result then left to move the remaining digits. The following is the optimized code:

Class Solution {public:    uint32_t reversebits (uint32_t N) {        uint32_t result=0;        int size = sizeof (uint32_t) *8;        int i=0;        Number of bits that have been moved        while (n!=0) {            result = result << 1;            result + = n%2;            n=n>>1;            i++;        }        Result <<= size-i;        return result;}    ;

[Leetcode] Reverse Bits