169. Majority Element

Given an array nums of size n, return the majority element.

The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array.

 

Example 1:

Input: nums = [3,2,3]
Output: 3
Example 2:

Input: nums = [2,2,1,1,1,2,2]
Output: 2
 

Constraints:

n == nums.length
1 <= n <= 5 * 104
-109 <= nums[i] <= 109
 

Follow-up: Could you solve the problem in linear time and in O(1) space?


solution:

class Solution {
    public int majorityElement(int[] nums) {
        int n = nums.length;
        Map<Integer,Integer> map = new HashMap<>();
        for(int i = 0;i<n;i++){
            map.put(nums[i],map.getOrDefault(nums[i],0)+1);
        }
        n = n/2;
        for(Map.Entry<Integer,Integer> entry: map.entrySet()){
            if(entry.getValue()> n){
                return entry.getKey();
            }
        }
        return 0;
    }
}