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All Permutations of a String

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 10

Write a JavaScript program to generate all possible permutations of a given string. A permutation is a rearrangement of the characters in the string. The function should return an array containing all unique permutations of the input string.

Example 1
    
      
  • Input: str = "abc"
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  • Output: ["abc", "acb", "bac", "bca", "cab", "cba"]
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  • Explanation: 
    • Starting with "abc", we can place 'a' in first position and permute "bc" to get "abc", "acb". 
    • Placing 'b' in first position and permuting "ac" gives us "bac", "bca". 
    • Placing 'c' in first position and permuting "ab" gives us "cab", "cba". 
    • All 6 permutations are generated using recursive backtracking.
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Example 2
    
      
  • Input: str = "ab"
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  • Output: ["ab", "ba"]
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  • Explanation: 
    • With string "ab", we can place 'a' first and get "ab". 
    • We can place 'b' first and get "ba". 
    • Total of 2 permutations are possible for a 2-character string.
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Constraints
    
      
  • 1 ≤ str.length ≤ 8
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  • str consists of unique lowercase English letters
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  • Time Complexity: O(n! * n) where n is length of string
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  • Space Complexity: O(n! * n) for storing all permutations
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  • The order of permutations in output array doesn't matter
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RecursionBacktracking DropboxD. E. Shaw
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Hint
Solution

Solution Hints

    
      
  • Use recursive backtracking to generate permutations
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  • For each position, try placing each remaining character
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  • Make a choice, recurse, then backtrack by undoing the choice
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  • Use a visited array or string manipulation to track used characters
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  • When the current permutation length equals string length, add to result
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  • Consider using array swapping for efficient character placement
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Steps to solve by this approach:

 Step 1: Create a result array to store all permutations and convert string to character array.

 Step 2: Define a recursive backtracking function that takes current permutation and remaining characters.

 Step 3: Set base case - when no characters remain, add current permutation to result.

 Step 4: For each remaining character, add it to current permutation (choose step).

 Step 5: Create new remaining array without the chosen character and recurse.

 Step 6: Remove the last added character from current permutation (backtrack step).

 Step 7: Return the result array containing all permutations.

Submitted Code :