给定数字n,请打印前n个正整数,并在其二进制表示形式中精确地包含两个设置位。
例子 :
Input: n = 3
Output: 3 5 6
The first 3 numbers with two set bits are 3 (0011),
5 (0101) and 6 (0110)
Input: n = 5
Output: 3 5 6 9 10 12
一个简单的解决方案是从1开始一个个地考虑所有正整数。对于每个数字,检查它是否恰好有两个置位比特。如果一个数字恰好有两个设置位,请打印该数字并递增这些数字的计数。
一个有效的解决方案是直接生成此类数字。如果我们清楚地观察到数字,则可以将其重写为pow(2,1)+ pow(2,0),pow(2,2)+ pow(2,0),pow(2,2)+ pow (2,1),pow(2,3)+ pow(2,0),pow(2,3)+ pow(2,1),pow(2,3)+ pow(2,2),…… …
可以根据两个设置位中的较高位以递增顺序生成所有数字。这个想法是一一固定两个位的较高位。对于当前较高的设置位,请考虑所有较低的位并打印形成的数字。
C++
// C++ program to print first n numbers
// with exactly two set bits
#include
using namespace std;
// Prints first n numbers with two set bits
void printTwoSetBitNums(int n)
{
// Initialize higher of two sets bits
int x = 1;
// Keep reducing n for every number
// with two set bits.
while (n > 0)
{
// Consider all lower set bits for
// current higher set bit
int y = 0;
while (y < x)
{
// Print current number
cout << (1 << x) + (1 << y) << " ";
// If we have found n numbers
n--;
if (n == 0)
return;
// Consider next lower bit for current
// higher bit.
y++;
}
// Increment higher set bit
x++;
}
}
// Driver code
int main()
{
printTwoSetBitNums(4);
return 0;
}
Java
// Java program to print first n numbers
// with exactly two set bits
import java.io.*;
class GFG
{
// Function to print first n numbers with two set bits
static void printTwoSetBitNums(int n)
{
// Initialize higher of two sets bits
int x = 1;
// Keep reducing n for every number
// with two set bits
while (n > 0)
{
// Consider all lower set bits for
// current higher set bit
int y = 0;
while (y < x)
{
// Print current number
System.out.print(((1 << x) + (1 << y)) +" ");
// If we have found n numbers
n--;
if (n == 0)
return;
// Consider next lower bit for current
// higher bit.
y++;
}
// Increment higher set bit
x++;
}
}
// Driver program
public static void main (String[] args)
{
int n = 4;
printTwoSetBitNums(n);
}
}
// This code is contributed by Pramod Kumar
Python3
# Python3 program to print first n
# numbers with exactly two set bits
# Prints first n numbers
# with two set bits
def printTwoSetBitNums(n) :
# Initialize higher of
# two sets bits
x = 1
# Keep reducing n for every
# number with two set bits.
while (n > 0) :
# Consider all lower set bits
# for current higher set bit
y = 0
while (y < x) :
# Print current number
print((1 << x) + (1 << y),
end = " " )
# If we have found n numbers
n -= 1
if (n == 0) :
return
# Consider next lower bit
# for current higher bit.
y += 1
# Increment higher set bit
x += 1
# Driver code
printTwoSetBitNums(4)
# This code is contributed
# by Smitha
C#
// C# program to print first n numbers
// with exactly two set bits
using System;
class GFG
{
// Function to print first n
// numbers with two set bits
static void printTwoSetBitNums(int n)
{
// Initialize higher of
// two sets bits
int x = 1;
// Keep reducing n for every
// number with two set bits
while (n > 0)
{
// Consider all lower set bits
// for current higher set bit
int y = 0;
while (y < x)
{
// Print current number
Console.Write(((1 << x) +
(1 << y)) +" ");
// If we have found n numbers
n--;
if (n == 0)
return;
// Consider next lower bit
// for current higher bit.
y++;
}
// Increment higher set bit
x++;
}
}
// Driver program
public static void Main()
{
int n = 4;
printTwoSetBitNums(n);
}
}
// This code is contributed by Anant Agarwal.
PHP
0)
{
// Consider all lower set
// bits for current higher
// set bit
$y = 0;
while ($y < $x)
{
// Print current number
echo (1 << $x) + (1 << $y), " ";
// If we have found n numbers
$n--;
if ($n == 0)
return;
// Consider next lower
// bit for current
// higher bit.
$y++;
}
// Increment higher set bit
$x++;
}
}
// Driver code
printTwoSetBitNums(4);
// This code is contributed by Ajit
?>
Javascript
输出 :
3 5 6 9