如何关闭数字中的特定位？
给定数字 n 和值 k，关闭 n 中的第 k 位。请注意，k = 1 表示最右边的位。 示例:
Input: n = 15, k = 1
Output: 14
Input: n = 14, k = 1
Output: 14
The rightmost bit was already off, so no change.
Input: n = 15, k = 2
Output: 13
Input: n = 15, k = 3
Output: 11
Input: n = 15, k = 4
Output: 7
Input: n = 15, k >= 5
Output: 15
其思想是使用按位<~(1<<(k–1))，我们得到一个除了第 k 位之外所有位都已设置的数。如果我们用 n 对这个表达式进行按位&，我们得到一个数，除了第 k 位为 0 之外，所有位都与 n 相同。 下面是上面想法的实现。
C++
#include <iostream>
using namespace std;
// Returns a number that has all bits same as n
// except the k'th bit which is made 0
int turnOffK(int n, int k)
{
// k must be greater than 0
if (k <= 0) return n;
// Do & of n with a number with all set bits except
// the k'th bit
return (n & ~(1 << (k - 1)));
}
// Driver program to test above function
int main()
{
int n = 15;
int k = 4;
cout << turnOffK(n, k);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to turn off a particular bit in a number
import java.io.*;
class TurnOff
{
// Function to returns a number that has all bits same as n
// except the k'th bit which is made 0
static int turnOffK(int n, int k)
{
// k must be greater than 0
if (k <= 0)
return n;
// Do & of n with a number with all set bits except
// the k'th bit
return (n & ~(1 << (k - 1)));
}
// Driver program
public static void main (String[] args)
{
int n = 15;
int k = 4;
System.out.println(turnOffK(n, k));
}
}
// Contributed by Pramod Kumar
Python 3
# Returns a number that
# has all bits same as n
# except the k'th bit
# which is made 0
def turnOffK(n,k):
# k must be greater than 0
if (k <= 0):
return n
# Do & of n with a number
# with all set bits except
# the k'th bit
return (n & ~(1 << (k - 1)))
# Driver code
n = 15
k = 4
print(turnOffK(n, k))
# This code is contributed
# by Anant Agarwal.
C
// C# program to turn off a
// particular bit in a number
using System;
class GFG
{
// Function to returns a number
// that has all bits same as n
// except the k'th bit which is
// made 0
static int turnOffK(int n, int k)
{
// k must be greater than 0
if (k <= 0)
return n;
// Do & of n with a number
// with all set bits except
// the k'th bit
return (n & ~ (1 << (k - 1)));
}
// Driver Code
public static void Main ()
{
int n = 15;
int k = 4;
Console.Write(turnOffK(n, k));
}
}
// This code is contributed by Nitin Mittal.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program to turn off a
// particular bit in a number
// Returns a number that has
// all bits same as n except
// the k'th bit which is made 0
function turnOffK($n, $k)
{
// k must be greater than 0
if ($k <= 0)
return $n;
// Do & of n with a number
// with all set bits except
// the k'th bit
return ($n & ~(1 << ($k - 1)));
}
// Driver Code
$n = 15;
$k = 4;
echo turnOffK($n, $k);
// This code is contributed by nitin mittal
?>
java 描述语言
<script>
// Returns a number that has all bits same as n
// except the k'th bit which is made 0
function turnOffK( n, k){
// k must be greater than 0
if (k <= 0) return n;
// Do & of n with a number with all set bits except
// the k'th bit
return (n & ~(1 << (k - 1)));
}
// Driver program to test above function
let n = 15;
let k = 4;
document.write(turnOffK(n, k));
// This code is contributed by rohitsingh07052.
</script>
输出:
7
练习:编写一个函数 turnOnK()，打开第 k 位。 本文由拉胡尔·贾恩供稿。如果您发现任何不正确的地方，请写评论，或者您想分享更多关于上面讨论的主题的信息
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