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Maximize the number by rearranging bits in C++
Problem statement
Given an unsigned number, find the maximum number that could be formed by using the bits of the given unsigned number
If the input number is 8 then its binary representation is−
00000000000000000000000000001000
To maximize it set MSB to 1. Then number becomes 2147483648 whose binary representation is−
10000000000000000000000000000000
Algorithms
1. Count number of set bits in the binary representation of a given number 2. Find a number with n least significant set bits 3. shift the number left by (32 – n)
Example
#include <bits/stdc++.h>
using namespace std;
unsigned getMaxNumber(unsigned num){
int n = __builtin_popcount(num);
if (n == 32) {
return num;
}
unsigned result = (1 << n) - 1;
return (result << (32 - n));
}
int main(){
unsigned n = 8;
cout << "Maximum number = " << getMaxNumber(n) << endl;
return 0;
}Output
When you compile and execute the above program. It generates the following output−
Maximum number = 2147483648
Updated on: 24-Dec-2019
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