Problem no 20: finding largest element in the array which is less than x.

 QUESTION:

 

Floor in a Sorted Array

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Given a sorted array arr[] of size N without duplicates, and given a value x. Floor of x is defined as the largest element K in arr[] such that K is smaller than or equal to x. Find the index of K(0-based indexing).

Example 1:

Input:
N = 7, x = 0 
arr[] = {1,2,8,10,11,12,19}
Output: -1
Explanation: No element less 
than 0 is found. So output 
is "-1".

Example 2:

Input:
N = 7, x = 5 
arr[] = {1,2,8,10,11,12,19}
Output: 1
Explanation: Largest Number less than 5 is
2 (i.e K = 2), whose index is 1(0-based 
indexing). 

ANSWER:

int findFloor(vector<long long> v, long long n, long long x)

{
 long long  max=INT_MIN;
 long long index;
  int singleelementpresentlessthanx=0;
 for(long long i=0;i<n;i++)
 {
     if(v[i]<=x)
     {
         singleelementpresentlessthanx=1;
         if(v[i]>max)
         {
             max=v[i];
             index=i;
         }
     }
 }
 
 if(singleelementpresentlessthanx==0)
 {
     return -1;
 }
 else
 {
     return index;
 }
 
 
}