不使用除法和乘法运算符计算 7n/8
原文:https://www . geeksforgeeks . org/calculate-7n 8-不使用除法和乘法运算符/
给定一个整数，编写一个函数来计算⌈7n/8⌉ ( 上限为 7n/8)，而不使用除法和乘法运算符。 强烈建议尽量减少浏览器，先自己试试这个。
方法 1: 思路是先计算 n/8 的楼层，即⌊n/8⌋使用右移按位运算符。表达式 n > > 3 产生同样的结果。如果我们从 n 中减去⌊n/8⌋，就得到⌈7n/8⌉
以下是上述想法的实现:
C++
// C++ program to evaluate ceil(7n/8)
// without using * and /
#include <iostream>
using namespace std;
int multiplyBySevenByEight(int n)
{
// Note the inner bracket here. This is needed
// because precedence of '-' operator is higher
// than '<<'
return (n - (n >> 3));
}
// Driver code
int main()
{
int n = 9;
cout << multiplyBySevenByEight(n);
return 0;
}
// This code is contributed by khushboogoyal499
C
// C program to evaluate ceil(7n/8) without using * and /
#include <stdio.h>
int multiplyBySevenByEight(unsigned int n)
{
/* Note the inner bracket here. This is needed
because precedence of '-' operator is higher
than '<<' */
return (n - (n >> 3));
}
/* Driver program to test above function */
int main()
{
unsigned int n = 9;
printf("%d", multiplyBySevenByEight(n));
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to evaluate ceil(7n/8)
// without using * and
import java.io.*;
class GFG {
static int multiplyBySevenByEight(int n)
{
/* Note the inner bracket here. This is needed
because precedence of '-' operator is higher
than '<<' */
return (n - (n >> 3));
}
// Driver code
public static void main(String args[])
{
int n = 9;
System.out.println(multiplyBySevenByEight(n));
}
}
// This code is contributed by Anshika Goyal.
Python 3
# Python program to evaluate ceil(7n/8) without using * and /
def multiplyBySevenByEight(n):
# Note the inner bracket here. This is needed
# because precedence of '-' operator is higher
# than '<<'
return (n - (n >> 3))
# Driver program to test above function */
n = 9
print(multiplyBySevenByEight(n))
# This code is contributed by
# Smitha Dinesh Semwal
C
// C# program to evaluate ceil(7n/8)
// without using * and
using System;
public class GFG {
static int multiplyBySevenByEight(int n)
{
/* Note the inner bracket here.
This is needed because precedence
of '-' operator is higher than
'<<' */
return (n - (n >> 3));
}
// Driver code
public static void Main()
{
int n = 9;
Console.WriteLine(multiplyBySevenByEight(n));
}
}
// This code is contributed by Sam007.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program to evaluate ceil
// (7n/8) without using * and
function multiplyBySevenByEight( $n)
{
// Note the inner bracket here.
// This is needed because
// precedence of '-' operator
// is higher than '<<'
return ($n - ($n >> 3));
}
// Driver Code
$n = 9;
echo multiplyBySevenByEight($n);
// This code is contributed by Ajit
?>
java 描述语言
<script>
// JavaScript program to evaluate ceil(7n/8) without using * and /
function multiplyBySevenByEight(n)
{
/* Note the inner bracket here. This is needed
because precedence of '-' operator is higher
than '<<' */
return (n - (n>>3));
}
/* Driver program to test above function */
let n = 9;
document.write(multiplyBySevenByEight(n));
// This code is contributed by Surbhi Tyagi.
</script>
输出:
8
时间复杂度: O(1)
辅助空间: O(1)
方法 2(总是与 7*n/8 匹配): 上述方法并不总是产生与“printf(% u，7n/8)”相同的结果。例如，对于 n = 15，表达式 7n/8 的值是 13，但是上面的程序产生 14。下面是始终匹配 7n/8 的修改版本。这个想法是首先将数字乘以 7，然后除以 8，就像表达式 7n/8 中发生的那样。
C++
// C++ program to evaluate 7n/8 without using * and /
#include<iostream>
using namespace std;
int multiplyBySevenByEight(unsigned int n)
{
/* Step 1) First multiply number by 7 i.e. 7n = (n << 3) -n
* Step 2) Divide result by 8 */
return ((n << 3) -n) >> 3;
}
/* Driver program to test above function */
int main()
{
unsigned int n = 15;
cout<<" "<< multiplyBySevenByEight(n);
return 0;
}
// This code is contributed by shivanisinghss2110
C
// C program to evaluate 7n/8 without using * and /
#include<stdio.h>
int multiplyBySevenByEight(unsigned int n)
{
/* Step 1) First multiply number by 7 i.e. 7n = (n << 3) -n
* Step 2) Divide result by 8 */
return ((n << 3) -n) >> 3;
}
/* Driver program to test above function */
int main()
{
unsigned int n = 15;
printf("%u", multiplyBySevenByEight(n));
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to evaluate 7n/8
// without using * and /
import java.io.*;
class GFG
{
static int multiplyBySevenByEight(int n)
{
// Step 1) First multiply number
// by 7 i.e. 7n = (n << 3) -n
// * Step 2) Divide result by 8
return ((n << 3) -n) >> 3;
}
// Driver program
public static void main(String args[])
{
int n = 15;
System.out.println(multiplyBySevenByEight(n));
}
}
// This code is contributed by Anshika Goyal.
Python 3
# Python3 program to evaluate 7n/8
# without using * and /
def multiplyBySevenByEight(n):
#Step 1) First multiply number
# by 7 i.e. 7n = (n << 3) -n
# Step 2) Divide result by 8
return ((n << 3) -n) >> 3;
# Driver code
n = 15;
print(multiplyBySevenByEight(n));
#this code is contributed by sam007.
C
// C# program to evaluate 7n/8
// without using * and /
using System;
public class GFG {
static int multiplyBySevenByEight(int n)
{
// Step 1) First multiply number
// by 7 i.e. 7n = (n << 3) -n
// * Step 2) Divide result by 8
return ((n << 3) -n) >> 3;
}
// Driver program
public static void Main()
{
int n = 15;
Console.WriteLine(
multiplyBySevenByEight(n));
}
}
// This code is contributed by Sam007.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program to evaluate 7n/8
// without using * and /
function multiplyBySevenByEight( $n)
{
/* Step 1) First multiply number by
7 i.e. 7n = (n << 3) - n
Step 2) Divide result by 8 */
return (($n << 3) -$n) >> 3;
}
// Driver Code
$n = 15;
echo multiplyBySevenByEight($n);
// This code is contributed by anuj_67.
?>
java 描述语言
<script>
// Javascript program to evaluate 7n/8
// without using * and /
function multiplyBySevenByEight(n)
{
// Step 1) First multiply number
// by 7 i.e. 7n = (n << 3) -n
// * Step 2) Divide result by 8
return ((n << 3) -n) >> 3;
}
// Driver code
var n = 15;
document.write(multiplyBySevenByEight(n));
// This code is contributed by shikhasingrajput
</script>
输出:
13
时间复杂度: O(1)
辅助空间: O(1)
注:两种方法的结果存在差异。方法 1 产生上限(7n/8)，但方法 2 产生整数值 7n/8。例如，对于 n = 15，第一种方法的结果是 14，但是对于第二种方法是 13。
感谢纳伦德拉·康拉尔卡 r 提出这个方法。 本文由拉杰夫供稿。如果您发现任何不正确的地方，或者您想分享更多关于上面讨论的主题的信息，请写评论
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