added majority element

algorithms/Python/arrays/majority_element.py

@@ -0,0 +1,26 @@
+"""
+Algorithm Type: Array Traversal
+Time Complexity: O(n)
+"""
+numbers = [2, 2, 5, 6, 2, 6, 2, 10, 2]
+
+def majority_element(numbers):
+    m = float("inf")
+    cnt = 0
+    for num in numbers:
+        if cnt == 0:
+            m = num
+            cnt += 1
+        elif m == num:
+            cnt += 1
+        else:
+            cnt -= 1
+    # to verify the most frequent number is greater than length of aaray//2
+    recheck_cnt = 0
+    for num in numbers:
+        if num == m:
+            recheck_cnt += 1
+    return m if recheck_cnt > len(numbers)//2 else None
+
+if __name__ == "__main__":
+  print(majority_element(numbers))