Majority Element

Problem Statement

Given an array arr[], find the majority element in the array.

A majority element is an element that appears strictly more than arr.size()/2 times.
If no majority element exists, return -1.
Examples
Input: arr = [1, 1, 2, 1, 3, 5, 1]
Output: 1

Explanation: 1 appears more than 7/2 = 3.5 times.

Input: arr = [7]
Output: 7

Explanation: Single element is trivially the majority.

Input: arr = [2, 13]
Output: -1

Explanation: No element appears more than 2/2 = 1 times.

Constraints
1 ≤ arr.size() ≤ 10^5
1 ≤ arr[i] ≤ 10^5

Approach : Use Hash Map

Count the frequency of each element using a dictionary. If an element count exceeds n//2, return it.

from typing import List

class Solution:
def majorityElement(self, arr: List[int]) -> int:
n = len(arr)
freq = {}

    for num in arr:
        freq[num] = freq.get(num, 0) + 1
        if freq[num] > n // 2:
            return num

    return -1