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Merge Two Dictionaries into One

Certification: Intermediate Level Accuracy: 83.33% Submissions: 6 Points: 5

Write a Python program that merges two dictionaries into one. If there are duplicate keys, the value from the second dictionary should overwrite the value from the first.

Example 1
    
  
  • Input 1: {'a': 1, 'b': 2}
    • 
  
  • Input 2: {'b': 3, 'c': 4}
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  • Output: {'a': 1, 'b': 3, 'c': 4}
    • 
  
  • Explanation: 
    
      
      
    • Step 1: Take the first dictionary {'a': 1, 'b': 2} and the second dictionary {'b': 3, 'c': 4}.
      • 
      
    • Step 2: Create a new dictionary with all key-value pairs from the first dictionary: {'a': 1, 'b': 2}.
      • 
      
    • Step 3: Add all key-value pairs from the second dictionary, overwriting any existing keys.
      • 
      
    • Step 4: The key 'b' appears in both dictionaries, so its value is updated to 3 from the second dictionary.
      • 
      
    • Step 5: Return the merged dictionary {'a': 1, 'b': 3, 'c': 4}.
      • 
    
    
  
    •
Example 2
    
  
  • Input 1: {'x': 5, 'y': 2}
    • 
  
  • Input 2: {'y': 8, 'z': 9}
    • 
  
  • Output: {'x': 5, 'y': 8, 'z': 9}
    • 
  
  • Explanation: 
    
      
      
    • Step 1: Take the first dictionary {'x': 5, 'y': 2} and the second dictionary {'y': 8, 'z': 9}.
      • 
      
    • Step 2: Create a new dictionary with all key-value pairs from the first dictionary: {'x': 5, 'y': 2}.
      • 
      
    • Step 3: Add all key-value pairs from the second dictionary, overwriting any existing keys.
      • 
      
    • Step 4: The key 'y' appears in both dictionaries, so its value is updated to 8 from the second dictionary.
      • 
      
    • Step 5: Return the merged dictionary {'x': 5, 'y': 8, 'z': 9}.
      • 
    
    
  
    •
Constraints
    
  
  • 1 ≤ len(d1), len(d2) ≤ 10^3
    • 
  
  • -10^5 ≤ d1[key], d2[key] ≤ 10^5
    • 
  
  • Time Complexity: O(n), where n is the total number of key-value pairs
    • 
  
  • Space Complexity: O(n)
    •
Dictionaries Deloitte
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Hint
Solution

Solution Hints

    
  
  • Use the ** operator to unpack and merge dictionaries.
    • 
  
  • Use the update() method to merge dictionaries in place.
    • 
  
  • Use dictionary comprehension to combine the dictionaries.
    •

Steps to solve by this approach:

 Step 1: Use dictionary unpacking with the ** operator.
 Step 2: Unpack the first dictionary (d1) into a new dictionary.
 Step 3: Unpack the second dictionary (d2) into the same new dictionary.
 Step 4: When keys overlap, values from d2 will override values from d1.
 Step 5: Return the merged dictionary containing all key-value pairs.
 Step 6: This approach is more concise than using the update() method.
 Step 7: Example: {'a': 1, 'b': 2} and {'b': 3, 'c': 4} merge to {'a': 1, 'b': 3, 'c': 4}.

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