给定一个数 x，求 y 使得 x*y + 1 不是素数
原文:https://www . geesforgeks . org/给定一个数字-x-find-y-so-xy-1-不是素数/
给定一个数 x，求 y (y > 0)，使得 xy + 1 不是素数。 例:*
Input : 2
Output : 4
Input : 5
Output : 3
观察:
x*(x-2) + 1 = (x-1)^2 不是素数。
方法:
For x > 2, y will be x-2 otherwise y will be x+2
C++
#include <bits/stdc++.h>
using namespace std;
int findY(int x)
{
if (x > 2)
return x - 2;
return x + 2;
}
// Driver code
int main()
{
int x = 5;
cout << findY(x);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// JAVA implementation of above approach
import java.util.*;
class GFG
{
public static int findY(int x)
{
if (x > 2)
return x - 2;
return x + 2;
}
// Driver code
public static void main(String [] args)
{
int x = 5;
System.out.println(findY(x));
}
}
// This code is contributed
// by ihritik
Python 3
# Python3 implementation of above
# approach
def findY(x):
if (x > 2):
return x - 2
return x + 2
# Driver code
if __name__=='__main__':
x = 5
print(findY(x))
# This code is contributed
# by ihritik
C
// C# implementation of above approach
using System;
class GFG
{
public static int findY(int x)
{
if (x > 2)
return x - 2;
return x + 2;
}
// Driver code
public static void Main()
{
int x = 5;
Console.WriteLine(findY(x));
}
}
// This code is contributed
// by Subhadeep
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP implementation of above approach
function findY($x)
{
if ($x > 2)
return $x - 2;
return $x + 2;
}
// Driver code
$x = 5;
echo (findY($x));
// This code is contributed
// by Shivi_Aggarwal
?>
java 描述语言
<script>
// JavaScript implementation of above approach
// Function to check whether it is possible
// or not to move from (0, 0) to (x, y)
// in exactly n steps
function findY(x)
{
if (x > 2)
return x - 2;
return x + 2;
}
// Driver code
var x = 5;
document.write(findY(x));
// This code is contributed by Ankita saini
</script>
输出:
3
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