小于等于给定数的 2 的最高幂
给定一个数 n，求小于或等于 n 的 2 的最高幂。
例:
Input : n = 10
Output : 8
Input : n = 19
Output : 16
Input : n = 32
Output : 32
一个简单的解决方案是从 n 开始检查，一直递减，直到我们找到 2 的幂。
c++
// C++ program to find highest power of 2 smaller
// than or equal to n.
#include<bits/stdc++.h>
using namespace std;
int highestPowerof2(int n)
{
int res = 0;
for (int i=n; i>=1; i--)
{
// If i is a power of 2
if ((i & (i-1)) == 0)
{
res = i;
break;
}
}
return res;
}
// Driver code
int main()
{
int n = 10;
cout << highestPowerof2(n);
return 0;
}
Java
// Java program to find highest power of
// 2 smaller than or equal to n.
class GFG{
static int highestPowerof2(int n)
{
int res = 0;
for(int i = n; i >= 1; i--)
{
// If i is a power of 2
if ((i & (i-1)) == 0)
{
res = i;
break;
}
}
return res;
}
// Driver code
public static void main(String[] args)
{
int n = 10;
System.out.print(highestPowerof2(n));
}
}
// This code is contributed by 29AjayKumar
python 3
# Python3 program to find highest
# power of 2 smaller than or
# equal to n.
def highestPowerof2(n):
res = 0;
for i in range(n, 0, -1):
# If i is a power of 2
if ((i & (i - 1)) == 0):
res = i;
break;
return res;
# Driver code
n = 10;
print(highestPowerof2(n));
# This code is contributed by mits
c
// C# code to find highest power
// of 2 smaller than or equal to n.
using System;
class GFG
{
public static int highestPowerof2(int n)
{
int res = 0;
for (int i = n; i >= 1; i--)
{
// If i is a power of 2
if ((i & (i - 1)) == 0)
{
res = i;
break;
}
}
return res;
}
// Driver Code
static public void Main ()
{
int n = 10;
Console.WriteLine(highestPowerof2(n));
}
}
// This code is contributed by ajit
PHP
<?php
// PHP program to find highest
// power of 2 smaller than or
// equal to n.
function highestPowerof2($n)
{
$res = 0;
for ($i = $n; $i >= 1; $i--)
{
// If i is a power of 2
if (($i & ($i - 1)) == 0)
{
$res = $i;
break;
}
}
return $res;
}
// Driver code
$n = 10;
echo highestPowerof2($n);
// This code is contributed by m_kit
?>
Javascript
<script>
// JavaScript program to find highest power
// of 2 smaller than or equal to n.
function highestPowerof2(n)
{
let res = 0;
for (let i = n; i >= 1; i--)
{
// If i is a power of 2
if ((i & (i - 1)) == 0)
{
res = i;
break;
}
}
return res;
}
// Driver code
let n = 10;
document.write(highestPowerof2(n));
</script>
输出
8
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