CBSE Class 12
Computer Science
06 Searching
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Q-1
Consider the following Python code implementing linear search. What will be printed?
Medium
Linear Search
Reference Code
```python
arr=[5,8,2,9]
key=2
for i in range(len(arr)):
if arr[i]==key:
print(i)
break
A
2
B
3
C
1
D
-1
Answer: 2
Explanation: Element 2 occurs at index position 2.
Q-2
Which condition must be satisfied before applying Binary Search?
Easy
Binary Search
A
Array must contain integers only
B
Array must be sorted
C
Array must contain unique values
D
Array must have even number of elements
Answer: Array must be sorted
Explanation: Binary search requires the data to be sorted.
Q-3
What will be printed after executing the following linear search code?
Medium
Linear Search
Reference Code
```python
arr=[4,7,9,2]
key=5
found=False
for x in arr:
if x==key:
found=True
print(found)
A
Error
B
5
C
False
D
True
Answer: False
Explanation: Element 5 is not present in the list.
Q-4
What will be the output of the following Binary Search code?
Medium
Binary Search
Reference Code
```python
arr=[2,4,6,8,10]
low=0
high=len(arr)-1
key=8
while low<=high:
mid=(low+high)//2
if arr[mid]==key:
print(mid)
break
elif arr[mid]<key:
low=mid+1
else:
high=mid-1
A
2
B
4
C
1
D
3
Answer: 3
Explanation: Element 8 is located at index 3.
Q-5
Which searching technique checks each element sequentially until the element is found?
Easy
Linear Search
A
Linear Search
B
Binary Search
C
Hash Search
D
Tree Search
Answer: Linear Search
Explanation: Linear search checks elements one by one.
Q-6
In Binary Search, which index is calculated first during each iteration?
Medium
Binary Search
A
low
B
mid
C
high
D
end
Answer: mid
Explanation: Binary search calculates the mid index first.
Q-7
What will be printed by the following code?
Medium
Linear Search
Reference Code
```python
arr=[3,6,9,12]
key=6
for i,v in enumerate(arr):
if v==key:
print(i)
A
3
B
1
C
0
D
2
Answer: 0
Explanation: Value 6 is at index 1.
Q-8
Which data structure is commonly used in hashing?
Medium
Search by Hashing
A
Stack
B
Queue
C
Array
D
Hash Table
Answer: Hash Table
Explanation: Hash tables store key-value pairs for fast lookup.
Q-9
What will be printed?
Easy
Introduction
Reference Code
```python
arr=[10,20,30,40]
print(30 in arr)
A
True
B
False
C
30
D
Error
Answer: True
Explanation: The 'in' operator checks membership.
Q-10
What is the average time complexity of Binary Search?
Medium
Binary Search
A
O(n)
B
O(log n)
C
O(n²)
D
O(1)
Answer: O(log n)
Explanation: Binary search reduces search space by half each step.
Q-11
How many comparisons are required in worst case for Linear Search with n elements?
Medium
Linear Search
A
log n
B
1
C
n
D
n²
Answer: n
Explanation: Worst case occurs when element is last or absent.
Q-12
Which search technique uses a hash function to compute storage location?
Medium
Search by Hashing
A
Binary Search
B
Linear Search
C
Tree Search
D
Hash Search
Answer: Hash Search
Explanation: Hash search uses hash function for direct indexing.
Q-13
Which statement describes Binary Search best?
Easy
Binary Search
A
Divides search interval into halves
B
Searches sequentially
C
Uses hashing table
D
Uses recursion only
Answer: Divides search interval into halves
Explanation: Binary search halves the search range each iteration.
Q-14
What is the best case complexity of Linear Search?
Medium
Linear Search
A
O(n)
B
O(1)
C
O(log n)
D
O(n²)
Answer: O(1)
Explanation: Best case occurs when element is first.
Q-15
Which structure stores key-value pairs for hashing?
Medium
Search by Hashing
A
Stack
B
Queue
C
Dictionary
D
Tree
Answer: Dictionary
Explanation: Python dictionaries implement hashing.
Q-16
What will be printed?
Easy
Search by Hashing
Reference Code
```python
d={'a':1,'b':2,'c':3}
print(d['b'])
A
1
B
3
C
b
D
2
Answer: 2
Explanation: Dictionary lookup uses hashing.
Q-17
Which algorithm is more efficient for large sorted datasets?
Easy
Binary Search
A
Binary Search
B
Linear Search
C
Sequential Search
D
Traversal
Answer: Binary Search
Explanation: Binary search performs faster for sorted lists.
Q-18
Which operation is performed in hashing to compute storage index?
Medium
Search by Hashing
A
Sorting
B
Hash Function
C
Binary Comparison
D
Index Traversal
Answer: Hash Function
Explanation: Hash function converts key into index.
Q-19
What will be printed?
Medium
Linear Search
Reference Code
```python
arr=[1,3,5,7]
print(arr.index(5))
A
5
B
3
C
2
D
1
Answer: 2
Explanation: Element 5 is at index position 2.
Q-20
Which search algorithm requires sorted input data?
Easy
Binary Search
A
Hash Search
B
Linear Search
C
Sequential Search
D
Binary Search
Answer: Binary Search
Explanation: Binary search requires sorted data.
Q-21
Which search algorithm compares the key with every element sequentially?
Easy
Linear Search
A
Linear Search
B
Binary Search
C
Hash Search
D
Graph Search
Answer: Linear Search
Explanation: Linear search checks elements one by one.
Q-22
Which operation determines mid index in Binary Search?
Medium
Binary Search
A
(low+high)
B
(low+high)//2
C
(low*high)
D
(high-low)
Answer: (low+high)//2
Explanation: Midpoint is calculated using integer division.
Q-23
What will be printed?
Easy
Introduction
Reference Code
```python
arr=[2,4,6,8]
print(7 in arr)
A
7
B
True
C
False
D
Error
Answer: False
Explanation: 7 is not present in the list.
Q-24
Which search technique provides constant average lookup time?
Medium
Search by Hashing
A
Linear Search
B
Binary Search
C
Tree Search
D
Hash Search
Answer: Hash Search
Explanation: Hash tables provide O(1) average lookup.
Q-25
Which structure is internally used by Python dictionary?
Medium
Search by Hashing
A
Hash Table
B
Binary Tree
C
Linked List
D
Queue
Answer: Hash Table
Explanation: Python dictionaries use hash tables.
Q-26
Which complexity describes worst case of Binary Search?
Medium
Binary Search
A
O(n)
B
O(log n)
C
O(n²)
D
O(1)
Answer: O(log n)
Explanation: Worst case still logarithmic.
Q-27
Which operation retrieves value using key in hashing?
Medium
Search by Hashing
A
Traversal
B
Sorting
C
Lookup
D
Insertion
Answer: Lookup
Explanation: Lookup retrieves value by key.
Q-28
Which technique divides search range repeatedly?
Easy
Binary Search
A
Linear Search
B
Sequential Search
C
Hash Search
D
Binary Search
Answer: Binary Search
Explanation: Binary search halves the range.
Q-29
Which searching technique is simplest to implement?
Easy
Linear Search
A
Linear Search
B
Binary Search
C
Hash Search
D
Tree Search
Answer: Linear Search
Explanation: Linear search requires simple sequential comparison.
Q-30
Which technique is fastest for exact key retrieval in large datasets?
Medium
Search by Hashing
A
Binary Search
B
Hashing
C
Linear Search
D
Traversal
Answer: Hashing
Explanation: Hashing provides near constant time lookup.
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