src/majority-element/res.js

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

  const getCount = (m, left, right) => {
    let count = 0;
    for (let i = left; i <= right; i++) {
      if (nums[i] === m) count += 1;
    }

    return count;
  }

  const getMajority = (left, right) => {
    if (left === right) return nums[left];
    const mid = (left + right) >> 1;

    const leftMajority = getMajority(left, mid);
    const rightMajority = getMajority(mid+1, right);

    if (leftMajority === rightMajority) return leftMajority;

    const lmCount = getCount(leftMajority, left, right);
    const rmCount = getCount(rightMajority, left, right);

    return lmCount > rmCount ? leftMajority : rightMajority;
  }

  return getMajority(0, len-1);
};