# Missing element of AP

QUESTION

Find the missing element from an ordered array A[ ], consisting of N elements representing an Arithmetic Progression (AP) .\n \n\nInput:\nThe first line of input contains an integer T denoting the number of test cases. Then T test cases follow. \nThe first line of each test case contains an integer N, where N is the size of the array A[ ].\nThe second line of each test case contains N space separated integers of an Arithmetic Progression denoting elements of the array A[ ].\n \n\nNote: The series should have a missing element in between a perfect A.P. with no missing element will not be considered.\n \n\nOutput:\nPrint out the missing element. \n \n\nConstraints:\n1 <= T <= 100\n2 <= N <= 10\n-50 <= A[i] <=50\n

``````#include<stdio.h>
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
int n,i;
scanf("%d",&n);
int a[n];
for(i=0;i<n;i++)
scanf("%d",&a[i]);
if(n==2)
printf("%d",(a+a)/2);
int d;
if(n==3)
{
if((a-a)<(a-a))
{
d=a-a;
printf("%d",a+d);
}
else
{
d=a-a;
printf("%d",a+d);
}

}
else
{
if((a-a)<(a-a))
d=a-a;
else
d=a-a;
for(i=1;i<n;i++)
{
if((a[i]-a[i-1])!=d){
printf("%d",a[i-1]+d);
break;
}
}
}
printf("\n");
}
}`````` 