# GATE Papers >> CSE >> 2017 >> Question No 48

Question No. 48

Let A be an array of 31 numbers consisting of a sequence of 0's followed by a sequence of 1's. The Problem is to find the smallest index i such that A[i] is 1 by probing the minimum number of locations in A. The worst case number of probes performed by an optimal algorithm is _________

##### Answer : 5.0 to 5.0

Solution of Question No 48 of GATE 2017 CSE Paper

Since 0 are followed by 1, so we have a sorted array of 0 and 1 and we can apply binary search algorithm with some modification, which will take maximum probes $\left[\log_2\;31\right]=5.$