Majority Number

Given an array of integers, the majority number is the number that occurs more than half of the size of the array. Find it.

Have you met this question in a real interview? 

Yes

Example

Given [1, 1, 1, 1, 2, 2, 2], return 1

Challenge

O(n) time and O(1) extra space

public class Solution {

    /**

     * @param nums: a list of integers

     * @return: find a  majority number

     */

    public int majorityNumber(ArrayList<Integer> nums) {

        // write your code

        if(nums == null || nums.size() == 0) return 0;

        int count = 1, cur = nums.get(0);

        for(int i = 1; i < nums.size(); i++){

            if(nums.get(i) == cur){

                count++;

            } else{

                count--;

            } 

            if(count == 0){

                count = 1;

                cur = nums.get(i);

            }

        }

        return cur;

        

    }

}