adding algo

src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_7.py

@@ -0,0 +1,22 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+
+        answer = dict()
+
+        for k, v in enumerate(nums):
+
+            if v in answer:
+                return [answer[v], k]
+            else:
+                answer[target - v]  = k
+
+        return []
+
+
+
+
+
+

src/my_project/interviews/amazon_high_frequency_23/common_algos/valid_palindrome_round_7.py

@@ -0,0 +1,24 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+import re
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+
+        # To lowercase 
+        s = s.lower()
+
+        # Remove non-alphanumeric characters
+        s = re.sub(pattern=r'[^a-zA-Z0-9]', repl='', string=s)
+
+        # Determine if s is palindrome or not
+        len_s = len(s)
+
+        for i in range(len_s//2):
+
+            if s[i] != s[len_s - 1 - i]:
+                return False 
+
+
+        return True 
+

src/my_project/interviews/top_150_questions_round_22/ex_96_letter_of_combinations_of_a_phone_number.py

@@ -0,0 +1,39 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+from collections import deque, defaultdict
+
+class Solution:
+    def letterCombinations(self, digits: str) -> List[str]:
+        if not digits:
+            return []
+
+        # Mapping of digits to letters
+        phone_map = {
+            '2': 'abc',
+            '3': 'def',
+            '4': 'ghi',
+            '5': 'jkl',
+            '6': 'mno',
+            '7': 'pqrs',
+            '8': 'tuv',
+            '9': 'wxyz'
+        }
+
+        result = []
+
+        def backtrack(index: int, current: str):
+            # Base case: if we've processed all digits
+            if index == len(digits):
+                result.append(current)
+                return
+
+            # Get the letters for the current digit
+            letters = phone_map[digits[index]]
+
+            # Try each letter and recurse
+            for letter in letters:
+                backtrack(index + 1, current + letter)
+
+        backtrack(0, "")
+        return result
+

src/my_project/interviews_typescript/top_150_questions_round_1/ex_96_letter_of_combinations_of_a_phone_number.ts

@@ -0,0 +1,38 @@
+function letterCombinations(digits: string): string[] {
+    if (!digits || digits.length === 0) {
+        return [];
+    }
+
+    // Mapping of digits to letters
+    const phoneMap: { [key: string]: string } = {
+        '2': 'abc',
+        '3': 'def',
+        '4': 'ghi',
+        '5': 'jkl',
+        '6': 'mno',
+        '7': 'pqrs',
+        '8': 'tuv',
+        '9': 'wxyz'
+    };
+
+    const result: string[] = [];
+
+    function backtrack(index: number, current: string): void {
+        // Base case: if we've processed all digits
+        if (index === digits.length) {
+            result.push(current);
+            return;
+        }
+
+        // Get the letters for the current digit
+        const letters = phoneMap[digits[index]];
+
+        // Try each letter and recurse
+        for (const letter of letters) {
+            backtrack(index + 1, current + letter);
+        }
+    }
+
+    backtrack(0, "");
+    return result;
+};

tests/test_150_questions_round_22/test_96_letter_of_combinations_of_a_phone_number_round_22.py

@@ -0,0 +1,42 @@
+import unittest
+from typing import Optional, List
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_96_letter_of_combinations_of_a_phone_number import Solution
+
+
+class LetterOfCombinationsOfAPhoneNumberTestCase(unittest.TestCase):
+    def setUp(self):
+        self.solution = Solution()
+
+    def test_example_1(self):
+        digits = "23"
+        expected = ["ad","ae","af","bd","be","bf","cd","ce","cf"]
+        result = self.solution.letterCombinations(digits)
+        self.assertEqual(sorted(result), sorted(expected))
+
+    def test_example_2(self):
+        digits = "2"
+        expected = ["a","b","c"]
+        result = self.solution.letterCombinations(digits)
+        self.assertEqual(sorted(result), sorted(expected))
+
+    def test_empty_string(self):
+        digits = ""
+        expected = []
+        result = self.solution.letterCombinations(digits)
+        self.assertEqual(result, expected)
+
+    def test_single_digit_9(self):
+        digits = "9"
+        expected = ["w", "x", "y", "z"]
+        result = self.solution.letterCombinations(digits)
+        self.assertEqual(sorted(result), sorted(expected))
+
+    def test_three_digits(self):
+        digits = "234"
+        # Should have 3 * 3 * 3 = 27 combinations
+        result = self.solution.letterCombinations(digits)
+        self.assertEqual(len(result), 27)
+        self.assertIn("adg", result)
+        self.assertIn("bfi", result)
+        self.assertIn("cfi", result)