Updated solution for 0017-Letter-Combinations-of-a-Phone-Number

Author: nishant0708

dsa-solutions/lc-solutions/0000-0099/0017-letter-combinations-of-a-phone-number.md

@@ -3,23 +3,21 @@ id: letter-combinations-of-a-phone-number
 title: Letter Combinations of a Phone Number (LeetCode)
 sidebar_label: 0017 Letter Combinations of a Phone Number
 tags:
-  - Back Tracking
-  - Mapping
-  - String
+    - Back Tracking
+    - Mapping
+    - String
 description: The problem requires generating all letter combinations corresponding to given digits (2-9). The solution utilizes backtracking to explore all combinations efficiently, employing a recursive approach in Java.
-sidebar_position: 17
 ---
 
 ## Problem Description
 
-| Problem Statement                                                                                             | Solution Link                                                                                                                                                                   | LeetCode Profile                                       |
-| :------------------------------------------------------------------------------------------------------------ | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | :----------------------------------------------------- |
-| [Letter Combinations of a Phone Number](https://leetcode.com/problems/Letter Combinations of a Phone Number/) | [Letter Combinations of a Phone Number Solution on LeetCode](https://leetcode.com/problems/Letter Combinations of a Phone Number/solutions/5055810/video-two-pointer-solution/) | [gabaniyash846](https://leetcode.com/u/gabaniyash846/) |
+| Problem Statement                                                                                           | Solution Link                                                                                                                               | LeetCode Profile                                   |
+| :----------------------------------------------------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------ | :------------------------------------------------- |
+| [Letter Combinations of a Phone Number](https://leetcode.com/problems/Letter Combinations of a Phone Number/)                                         | [Letter Combinations of a Phone Number Solution on LeetCode](https://leetcode.com/problems/Letter Combinations of a Phone Number/solutions/5055810/video-two-pointer-solution/) | [gabaniyash846](https://leetcode.com/u/gabaniyash846/) |
 
 ### Problem Description
 
 ## Problem Statement:
-
 Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.
 
 ### Examples
@@ -34,6 +32,7 @@ Given a string containing digits from 2-9 inclusive, return all possible letter
 - **Input:** `digits = ""`
 - **Output:** `[]`
 
+
 #### Example 3
 
 - **Input:** `2`
@@ -49,11 +48,9 @@ Given a string containing digits from 2-9 inclusive, return all possible letter
 ### Approach
 
 1. **Mapping Digits to Letters:**
-
    - Define a mapping of digits to their corresponding letters, similar to telephone buttons.
 
 2. **Backtracking Function:**
-
    - Define a recursive backtracking function to generate all possible combinations.
    - The function takes four parameters:
      - `index`: The current index in the digits string.
@@ -63,7 +60,6 @@ Given a string containing digits from 2-9 inclusive, return all possible letter
    - After the recursive call, we remove the last character from the combination (backtracking).
 
 3. **Base Case:**
-
    - If the length of the current combination is equal to the length of the input digits string, we add the combination to the result list.
 
 4. **Main Function:**
@@ -159,7 +155,6 @@ public class Solution {
 ```
 
 #### CPP:
-
 ```cpp
 #include <iostream>
 #include <vector>
@@ -215,82 +210,80 @@ int main() {
 ```
 
 #### JavaScript
-
 ```js
 /**
  * @param {string} digits
  * @return {string[]}
  */
-var letterCombinations = function (digits) {
-  if (digits.length === 0) return [];
-
-  const digitToLetters = {
-    2: "abc",
-    3: "def",
-    4: "ghi",
-    5: "jkl",
-    6: "mno",
-    7: "pqrs",
-    8: "tuv",
-    9: "wxyz",
-  };
-
-  const combinations = [];
-
-  const backtrack = (index, path) => {
-    if (index === digits.length) {
-      combinations.push(path);
-      return;
-    }
-    const letters = digitToLetters[digits.charAt(index)];
-    for (let letter of letters) {
-      backtrack(index + 1, path + letter);
-    }
-  };
-
-  backtrack(0, "");
-  return combinations;
+var letterCombinations = function(digits) {
+    if (digits.length === 0) return [];
+    
+    const digitToLetters = {
+        '2': 'abc',
+        '3': 'def',
+        '4': 'ghi',
+        '5': 'jkl',
+        '6': 'mno',
+        '7': 'pqrs',
+        '8': 'tuv',
+        '9': 'wxyz'
+    };
+    
+    const combinations = [];
+    
+    const backtrack = (index, path) => {
+        if (index === digits.length) {
+            combinations.push(path);
+            return;
+        }
+        const letters = digitToLetters[digits.charAt(index)];
+        for (let letter of letters) {
+            backtrack(index + 1, path + letter);
+        }
+    };
+    
+    backtrack(0, '');
+    return combinations;
 };
 
 // Example usage:
 console.log(letterCombinations("23")); // Output: ["ad","ae","af","bd","be","bf","cd","ce","cf"]
 ```
 
 #### TypeScript
-
 ```ts
 class Solution {
-  private digitToLetters: { [key: string]: string } = {
-    "2": "abc",
-    "3": "def",
-    "4": "ghi",
-    "5": "jkl",
-    "6": "mno",
-    "7": "pqrs",
-    "8": "tuv",
-    "9": "wxyz",
-  };
-
-  letterCombinations(digits: string): string[] {
-    const combinations: string[] = [];
-
-    const backtrack = (index: number, path: string): void => {
-      if (index === digits.length) {
-        combinations.push(path);
-        return;
-      }
-      const letters = this.digitToLetters[digits.charAt(index)];
-      for (let letter of letters) {
-        backtrack(index + 1, path + letter);
-      }
+    private digitToLetters: { [key: string]: string } = {
+        '2': 'abc',
+        '3': 'def',
+        '4': 'ghi',
+        '5': 'jkl',
+        '6': 'mno',
+        '7': 'pqrs',
+        '8': 'tuv',
+        '9': 'wxyz'
     };
 
-    if (digits.length !== 0) {
-      backtrack(0, "");
-    }
+    letterCombinations(digits: string): string[] {
+        const combinations: string[] = [];
+
+        const backtrack = (index: number, path: string): void => {
+            if (index === digits.length) {
+                combinations.push(path);
+                return;
+            }
+            const letters = this.digitToLetters[digits.charAt(index)];
+            for (let letter of letters) {
+                backtrack(index + 1, path + letter);
+            }
+        };
 
-    return combinations;
-  }
+        if (digits.length !== 0) {
+            backtrack(0, '');
+        }
+        
+        return combinations;
+    }
 }
 
 // Example usage:
@@ -303,11 +296,9 @@ console.log(solution.letterCombinations("23")); // Output: ["ad","ae","af","bd",
 Here's a step-by-step algorithm for generating all possible letter combinations of a given string of digits using backtracking:
 
 1. **Define a mapping of digits to letters:**
-
    - Create a map where each digit from 2 to 9 is mapped to its corresponding letters on a telephone keypad.
 
 2. **Define a backtracking function:**
-
    - The function will take the following parameters:
      - `index`: The current index in the digits string.
      - `path`: The current combination of letters.
@@ -316,12 +307,11 @@ Here's a step-by-step algorithm for generating all possible letter combinations
    - After the recursive call, remove the last character from the combination (backtracking).
 
 3. **Base Case:**
-
    - If the length of the current combination is equal to the length of the input digits string, add the combination to the result list.
 
 4. **Main Function:**
    - Initialize an empty list to store the combinations.
    - Call the backtracking function with the initial index set to 0 and an empty string as the initial combination.
    - Return the list of combinations.
 
-This algorithm ensures that all possible combinations are generated by exploring all valid paths through backtracking.
+This algorithm ensures that all possible combinations are generated by exploring all valid paths through backtracking.