Skip to content
Related Articles

Related Articles

Improve Article

GATE | GATE CS 1996 | Question 66

  • Last Updated : 24 Mar, 2019

Consider the following program that attempts to locate an element x in a sorted array a[ ] using binary search. Assume N>1. The program is erroneous. Under what conditions does the program fail?

var i,j,k: integer;  x: integer;
    a: array; [1....N] of integer;
begin    i:= 1; j:= N;
    k:(i+j) div 2;
    if a[k] < x then i:= k 
    else j:= k 
until (a[k] = x) or (i >= j);
if (a[k] = x) then
    writeln ('x is in the array')
    writeln ('x is not in the array')

(A) x is the last element of the array a[]
(B) x is greater than all elements of the array a[]
(C) Both of the Above
(D) x is less than the last element of the array a[]

Answer: (C)

Explanation: The above program doesn’t work for the cases where element to be searched is the last element of a[] or greater than the last element (or maximum element) in a[]. For such cases, program goes in an infinite loop because i is assigned value as k in all iterations, and i never becomes equal to or greater than j. So while condition never becomes false.

Quiz of this Question

Attention reader! Don’t stop learning now.  Practice GATE exam well before the actual exam with the subject-wise and overall quizzes available in GATE Test Series Course.

Learn all GATE CS concepts with Free Live Classes on our youtube channel.

My Personal Notes arrow_drop_up
Recommended Articles
Page :