package algorithms;

/**

* Finds the missing number in an arithmetic progression.

*

* @author joeytawadrous

*/

public class ArithmeticProgression

{

public static void main(String[] args)

{

int[] list = {1, 3, 7};

System.out.println(findMissing(list));

}

/**

* Finds the missing number in an arithmetic progression.

* @param list

* @return missing number in progression

*/

public static int findMissing(int[] list)

{

int length = list.length;

int sum = (length + 1) * (list[0] + list[length - 1]) / 2;

for(int i = 0; i < length; i++)

{

sum -= list[i];

}

return sum;

}

}