使用给定数字的设置位的最小数字

给定无符号数，请使用给定无符号数的位找到可以形成的最小数。

例子 ：

Input : 6
Output : 3
Binary representation of 6 is 0000….0110. Smallest number with same number of set bits 0000….0011.
 
Input : 11
Output : 7

简单方法：
1.使用简单的十进制到二进制表示技术查找数字的二进制表示形式。
2.计数二进制表示中等于“ n”的置位位数。
3.创建一个将“ n”个最低有效位设置为1的二进制表示形式。
4.将二进制表示形式转换回数字。

高效方法：
1.只需测量数字的位表示形式中存在的1的数量即可。
2.(设置位的数量提高到2的幂)– 1表示最小数量。

C++

// An efficient C++ program to find
// minimum number formed by bits of a given number.
#include 
#define ll unsigned int
using namespace std;
  
// Returns minimum number formed by
// bits of a given number.
ll minimize(ll a)
{
    // _popcnt32(a) gives number of 1's 
    // present in binary representation 
    // of a.
    ll n = _popcnt32(a);
  
    return (pow(2, n) - 1);
}
  
// Driver function.
int main()
{
    ll a = 11;
    cout << minimize(a) << endl;
    return 0;
}

Java

// An efficient Java program to 
// find minimum number formed
// by bits of a given number.
import java.io.*;
  
class GFG
{
    public static int _popcnt32(long number) 
    {
        int count = 0;
        while (number > 0)
        {
            count += number & 1L;
            number >>= 1L;
        }
        return count;
    }
      
    // Returns minimum number formed 
    // by bits of a given number.
    static long minimize(long a)
    {
        // _popcnt32(a) gives number 
        // of 1's present in binary 
        // representation of a.
        int n = _popcnt32(a);
  
        return ((long)Math.pow(2, n) - 1);
    }
      
    // Driver Code.
    public static void main(String args[])
    {
        long a = 11;
        System.out.print(minimize(a));
    }
}
  
// This code is contributed by 
// Manish Shaw(manishshaw1)

Python3

# An efficient Python3 program 
# to find minimum number formed
# by bits of a given number.
  
# Returns minimum number formed by
# bits of a given number.
def minimize(a):
      
    # _popcnt32(a) gives number of 1's
    # present in binary representation
    # of a.
    n = bin(a).count("1")
  
    return (pow(2, n) - 1)
  
# Driver Code
a = 11
print(minimize(a))
  
# This code is contributed by Mohit Kumar

C#

// An efficient C# program to 
// find minimum number formed
// by bits of a given number.
using System;
using System.Linq;
using System.Collections.Generic;
  
class GFG
{
    // Returns minimum number formed 
    // by bits of a given number.
    static long minimize(long a)
    {
        // _popcnt32(a) gives number 
        // of 1's present in binary  
        // representation of a.
        string binaryString = Convert.ToString(a, 2);
        int n = binaryString.Split(new [] {'0'}, 
                StringSplitOptions.RemoveEmptyEntries).Length + 1;
  
        return ((long)Math.Pow(2, n) - 1);
    }
      
    // Driver Code.
    static void Main()
    {
        long a = 11;
        Console.Write(minimize(a));
    }
}
  
// This code is contributed by 
// Manish Shaw(manishshaw1)

输出 ：

7

注意：上面的代码使用GCC特定的功能。如果我们希望为其他编译器编写代码，则可以使用整数形式的Count设置位。

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