Majority_Element.js

/*
Majority Element
https://leetcode.com/problems/majority-element/

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

Note: You should have a better solution than O(N)
*/

/**
 * @param {number[]} nums
 * @return {number}
 */
var majorityElement = function (nums) {
  if (nums.length === 0) return -1;

  var candidate = nums[0];
  var proves = 1;

  for (var i = 1; i < nums.length; i++) {
    if (nums[i] === candidate) proves++;
    else {
      proves--;
      if (proves === 0) {
        candidate = nums[i];
        proves = 1;
      }
    }
  }

  return candidate;
};

module.exports.majorityElement = majorityElement;