adding algo

src/my_project/interviews/top_150_questions_round_21/majority_element.py

@@ -0,0 +1,20 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class Solution:
+    def majorityElement(self, nums: List[int]) -> int:
+
+        dic_answer = dict()
+        len_nums = len(nums)
+
+        for i in range(len_nums):
+
+            if nums[i] not in dic_answer:
+                dic_answer[nums[i]] = 1
+            else:
+                dic_answer[nums[i]] += 1
+
+            if dic_answer[nums[i]] > len_nums//2:
+                return nums[i]
+
+        return -1

tests/test_150_questions_round_21/test_majority_element_round_21.py

@@ -0,0 +1,17 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_21\
+.majority_element import Solution
+
+class MajorityElementTestCase(unittest.TestCase):
+
+    def test_is_major_element(self):
+        solution = Solution()
+        output = solution.majorityElement(nums=[3,2,3])
+        target = 3
+        self.assertEqual(output, target)
+
+    def test_is_no_major_element(self):
+        solution = Solution()
+        output = solution.majorityElement(nums = [1,2,3])
+        target = -1
+        self.assertEqual(output, target)