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Count Characters in a String

Certification: Basic Level Accuracy: 0% Submissions: 0 Points: 5

Write a JavaScript program to count the frequency of each character in a given string. The function should return an object where keys are characters and values are their frequencies. Consider both uppercase and lowercase letters as different characters.

Example 1
    
      
  • Input: str = "hello"
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  • Output: {h: 1, e: 1, l: 2, o: 1}
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  • Explanation: 
    • The string "hello" is processed character by character. 
    • 'h' appears 1 time, 'e' appears 1 time, 'l' appears 2 times, 'o' appears 1 time. 
    • Therefore, the character count is {h: 1, e: 1, l: 2, o: 1}.
    •
Example 2
    
      
  • Input: str = "Programming"
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  • Output: {P: 1, r: 2, o: 1, g: 2, a: 1, m: 2, i: 1, n: 1}
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  • Explanation: 
    • The string "Programming" contains both uppercase and lowercase letters. 
    • Each character is counted separately: P=1, r=2, o=1, g=2, a=1, m=2, i=1, n=1. 
    • Case sensitivity is maintained in the character counting.
    •
Constraints
    
      
  • 0 ≤ str.length ≤ 1000
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  • str consists of printable ASCII characters
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  • Time Complexity: O(n)
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  • Space Complexity: O(k) where k is the number of unique characters
    •
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Hint
Solution

Solution Hints

    
      
  • Initialize an empty object to store character frequencies
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  • Iterate through each character in the string using a loop
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  • For each character, check if it already exists in the frequency object
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  • If it exists, increment its count; if not, initialize it to 1
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  • Return the frequency object after processing all characters
    •

Steps to solve by this approach:

 Step 1: Initialize an empty object to store character frequency mappings
 Step 2: Create a loop to iterate through each character in the input string
 Step 3: For each character, check if it already exists as a key in the object
 Step 4: If the character exists, increment its value by 1
 Step 5: If the character doesn't exist, create a new key-value pair with count 1
 Step 6: Continue iteration until all characters have been processed
 Step 7: Return the completed character frequency object

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