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Position of a person diametrically opposite on a circle
  • Last Updated : 18 Mar, 2021

There are n people standing on the circumference of a circle. Given the position of a persom m, the task is to find the position of the person standing diametrically opposite to m on the circle. 
 

position of a person diametrically opposite to him in circle

Examples: 
 

Input: n = 6, m = 2 
Output:
Position 5 is opposite to 2 when there are 6 positions in total
Input: n = 8, m = 5 
Output:
 

 



Approach: There are two cases: 
 

  • If m > n / 2 then answer will always be m – (n / 2).
  • If m ≤ n / 2 then answer will always be m + (n / 2).

Below is the implementation of the above approach: 
 

C++




// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to return the required position
int getPosition(int n, int m)
{
    if (m > (n / 2))
        return (m - (n / 2));
 
    return (m + (n / 2));
}
 
// Driver code
int main()
{
    int n = 8, m = 5;
    cout << getPosition(n, m);
 
    return 0;
}

Java




// Java implementation of the approach
class Sol
{
 
// Function to return the required position
static int getPosition(int n, int m)
{
    if (m > (n / 2))
        return (m - (n / 2));
 
    return (m + (n / 2));
}
 
// Driver code
public static void main(String args[])
{
    int n = 8, m = 5;
    System.out.println(getPosition(n, m));
 
}
}
// This code is contributed by Arnab Kundu

Python3




# Python3 implementation of the approach
 
# Function to return the
# required position
def getPosition(n, m):
 
    if (m > (n // 2)) :
        return (m - (n // 2))
 
    return (m + (n // 2))
 
# Driver code
n = 8
m = 5
print(getPosition(n, m))
 
# This code is contributed
# by ihritik

C#




// C# implementation of the approach
using System;
 
class GFG
{
     
// Function to return the required position
static int getPosition(int n, int m)
{
    if (m > (n / 2))
        return (m - (n / 2));
 
    return (m + (n / 2));
}
 
    // Driver code
    static public void Main ()
    {
         
    int n = 8, m = 5;
    Console.WriteLine(getPosition(n, m));
    }
}
 
// This code is contributed by ajit.

PHP




<?php
// PHP implementation of the approach
 
// Function to return the
// required position
function getPosition($n, $m)
{
 
    if ($m > ($n / 2))
        return ($m - ($n / 2));
 
    return ($m + ($n / 2));
}
 
// Driver code
$n = 8;
$m = 5;
echo getPosition($n, $m);
 
// This code is contributed
// by ihritik
?>

Javascript




<script>
 
// Javascript implementation of the approach
 
// Function to return the required position
function getPosition( n, m)
{
    if (m > (n / 2))
        return (m - parseInt(n / 2));
 
    return (m + parseInt(n / 2));
}
 
// Driver code
var n = 8, m = 5;
document.write(getPosition(n, m));
 
</script>
Output: 
1

 

Time Complexity: O(1)
 

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