QUESTION

Given a sorted array, arr[] and a value, x, find floor of x in given array. Floor of x is the largest element in arr[] such that the element is smaller than or equal to x. If floor exists, then return index of it, else return -1

ANSWER

#include <stdio.h>
int Floor(int key, int*a,int low, int high,int size)
{
  if(low>high)
  {
    if(low==0)
      return -1;
    else
      return high -1;
  }
  int mid=(low+high)/2;
  if(key==a[mid])
  {
    while(a[mid]==a[mid+1])
      mid++;
    return mid;
  }
  else if (key<a[mid])
  {
    if(key>a[mid-1])
    return mid -1;
    Floor(key,a,low,mid-1,size);
  }
  else
  {
    if(key < a[mid+1])
      return mid;
    Floor(key,a,mid+1,high,size);
  }
}
int main()
{
int arr[100],x,t,n,i;
  scanf("%d",&t);
  while(t--)
  {
    scanf("%d",&n);
    scanf("%d",&x);
    for(i=0;i<n;i++)
      scanf("%d",&arr[i]);
    printf("%d\n",Floor(x,arr,0,n,n));
  }
	return 0;
}