LeetCode169 Majority Element 求衆數

1. problem description

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.

You may assume that the array is non-empty and the majority element always exist in the array.

Example 1:
Input: [3,2,3]
Output: 3

Example 2:
Input: [2,2,1,1,1,2,2]
Output: 2

solution

class Solution {
public:
    int majorityElement(vector<int>& nums) {
        unordered_map<int, int> counter;
        for (int num : nums) {
            if (++counter[num] > nums.size() / 2) {
                return num;
            }
        }
        return 0;
    }
};