Merge pull request #2577 from dnoice/master

update two_num.py

Author: geekcomputers

two_num.py

@@ -1,26 +1,58 @@
-"""Author Anurag Kumar (mailto:[email protected])
+"""
+Author: Anurag Kumar (mailto:[email protected])
 
-Given an array of integers, return indices of the two numbers
-such that they add up to a specific target.
-You may assume that each input would have exactly one solution,
-and you may not use the same element twice.
+Description:
+    This function finds two numbers in a given list that add up to a specified target. 
+    It returns the indices of those two numbers.
 
-Example:
-Given nums = [2, 7, 11, 15], target = 9,
-Because nums[0] + nums[1] = 2 + 7 = 9,
-return [0, 1].
+Constraints:
+    - Each input will have exactly one solution.
+    - The same element cannot be used twice.
 
+Example:
+    >>> two_sum([2, 7, 11, 15], 9)
+    [0, 1]
 """
 
+from typing import List, Optional
+
+def two_sum(nums: List[int], target: int) -> Optional[List[int]]:
+    """
+    Finds indices of two numbers in 'nums' that add up to 'target'.
+
+    Args:
+        nums (List[int]): List of integers.
+        target (int): Target sum.
+
+    Returns:
+        Optional[List[int]]: Indices of the two numbers that add up to the target,
+                             or None if no such pair is found.
+    """
+    if len(nums) < 2:
+        raise ValueError("Input list must contain at least two numbers.")
+    
+    if not all(isinstance(num, int) for num in nums):
+        raise TypeError("All elements in the list must be integers.")
+    
+    # Dictionary to track seen values and their indices
+    seen_values = {}
+
+    for index, value in enumerate(nums):
+        complement = target - value
+        if complement in seen_values:
+            return [seen_values[complement], index]
+        seen_values[value] = index
+
+    return None
+
+# Example usage
+if __name__ == "__main__":
+    example_nums = [2, 7, 11, 15]
+    example_target = 9
+    result = two_sum(example_nums, example_target)
 
-def twoSum(nums, target):
-    chk_map = {}
-    for index, val in enumerate(nums):
-        compl = target - val
-        if compl in chk_map:
-            indices = [chk_map[compl], index]
-            print(indices)
-            return [indices]
-        else:
-            chk_map[val] = index
-    return False
+    if result:
+        num1, num2 = example_nums[result[0]], example_nums[result[1]]
+        print(f"Indices that add up to {example_target}: {result} (Values: {num1} + {num2})")
+    else:
+        print(f"No combination found that adds up to {example_target}.")