Find the Majority Element in the Array

Tuhin-thinks · Tuhin-thinks · commit d24bb8fdb54d · 2020-06-25T09:54:13.000+05:30
diff --git a/Majoirty_Eelement.py b/Majoirty_Eelement.py
@@ -0,0 +1,78 @@
+"""
+Given an array A of N elements. Find the majority element in the array. A majority element in an array A of size N is an element that appears more than N/2 times in the array.
+
+Input:
+The first line of the input contains T denoting the number of testcases. The first line of the test case will be the size of array and second line will be the elements of the array.
+
+Output:
+For each test case the output will be the majority element of the array. Output "-1" if no majority element is there in the array.
+
+User Task:
+The task is to complete the function findMajority() which finds the majority element in the array. If no majority exists, return -1.
+
+Expected Time Complexity: O(N).
+Expected Auxiliary Space: O(1).
+
+Constraints:
+1 <= T<= 100
+1 <= N <= 107
+0 <= Ai <= 106
+
+Example:
+Input:
+2
+5
+3 1 3 3 2
+3
+1 2 3
+
+Output:
+3
+-1
+
+Explanation:
+Testcase 1: Since, 3 is present more than N/2 times, so it is the majority element.
+Testcase 2: Since, each element in {1,2,3} appears only once so there is no majority element.
+"""
+
+
+# Complete this function
+def majorityElement(A, N):
+    # Your code here
+    weight_dict = {}
+    for elem in A:
+        if elem not in weight_dict.keys():
+            weight_dict[elem] = 1
+        else:
+            weight_dict[elem] += 1
+
+    for item, weight in weight_dict.items():
+        if weight > int(N / 2):
+            return item
+    return -1
+
+
+# {
+#  Driver Code Starts
+# Initial Template for Python 3
+
+import math
+
+from sys import stdin
+
+
+def main():
+    T = int(input())
+    while T > 0:
+        N = int(input())
+
+        A = [int(x) for x in input().strip().split()]
+
+        print(majorityElement(A, N))
+
+        T -= 1
+
+
+if __name__ == "__main__":
+    main()
+# } Driver Code Ends
