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Check if a List Contains a Sublist

Certification: Intermediate Level Accuracy: 37.7% Submissions: 61 Points: 10

Write a Python function to check if a given list contains another list as a sublist.

Example 1
    
  
  • Input: main_list = [1, 2, 3, 4, 5], sublist = [2, 3]
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  • Output: True
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  • Explanation: 
      
    
    • Step 1: Check if [2, 3] exists as a contiguous subsequence in [1, 2, 3, 4, 5].
      • 
    
    • Step 2: Start comparing from index 0 of main_list: [1, 2, 3, 4, 5]. No match at position 0.
      • 
    
    • Step 3: Try from index 1: [1, 2, 3, 4, 5]. Found match: 2 matches 2.
      • 
    
    • Step 4: Check next element: 3 matches 3.
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    • Step 5: All elements in sublist are found in sequence, so return True.
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    •
Example 2
    
  
  • Input: main_list = [1, 2, 3, 4, 5], sublist = [3, 5]
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  • Output: False
    • 
  
  • Explanation: 
      
    
    • Step 1: Check if [3, 5] exists as a contiguous subsequence in [1, 2, 3, 4, 5].
      • 
    
    • Step 2: Start comparing from index 0 of main_list: [1, 2, 3, 4, 5]. No match at position 0.
      • 
    
    • Step 3: Try from index 1: [1, 2, 3, 4, 5]. No match at position 1.
      • 
    
    • Step 4: Try from index 2: [1, 2, 3, 4, 5]. Found match: 3 matches 3.
      • 
    
    • Step 5: Check next element: 4 does not match 5.
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    • Step 6: No continuous sequence found matching the sublist, so return False.
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    •
Constraints
    
  
  • 1 <= len(main_list), len(sublist) <= 1000
    • 
  
  • Time Complexity: O(n * m) where n is the length of the main list and m is the length of the sublist
    • 
  
  • Space Complexity: O(1)
    •
Control StructuresListGoogleTCS (Tata Consultancy Services)
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Hint
Solution

Solution Hints

    
  
  • Use nested loops to check if the sublist exists in the main list.
    • 
  
  • Handle edge cases where the sublist is empty or longer than the main list.
    •

Steps to solve by this approach:

 Step 1: Handle edge cases - empty sublist is always contained in any list
 
 Step 2: Check if sublist is longer than main_list (impossible to contain)

 Step 3: Iterate through main_list up to the position where sublist can still fit

 Step 4: At each position i, check if the slice main_list[i:i+len(sublist)] equals sublist

 Step 5: If a match is found, return True

 Step 6: If no match is found after complete iteration, return False

 Step 7: Return the result, indicating whether sublist exists within main_list

Submitted Code :