Find two elements which will sum up to a given value, in a Sorted Array.

Given sorted integer array and a given value we have to find two elements which will sum up to a given value.

Since it is a sorted array our job is so easy.

For example, array a is having n element in sorted order
A[0]<A[1]<A[2]<........<A[n-1];

From this we can deduce that,
A[0]+A[1]<A[0]+A[2]<A[0]+A[3].......;
A[0]+A[n-1]<A[1]+A[n-1]<.....<A[n-2]+A[n-1];

Compare from the extreme summations with the given value and increase or decrease the indexes according to the comparison.

Int a[SIZE];
Int a[SIZE];
int n;

void findTwoElementsToN(int a[],int n){
 int i=0;
 int j=sizeof(a)/sizeof(int) -1;
 int sum=0;

 if(i<j){
  sum=a[i]+a[j];
  if(sum<n){
   i++;
  }else if(sum>n){
   j--;
  }else{
    printf(“%d and %d”,a[i],a[j]);
  }
 }
}