方法：分支法，将数据进行对半分割处理，类似归并排序

    1. class Solution {
    2. public:
    3.     int majorityElement(vector<int>& nums) {
    4.         return divide(nums,0,nums.size()-1);
    5.     }
    6.     int divide(vector<int>& nums,int left,int right){
    7.         if(left==right){
    8.             return nums[left];
    9.         }
    10.         int mid=(left+right)/2;
    11.         int left_ma=divide(nums,left,mid);
    12.         int right_ma=divide(nums,mid+1,right);
    13.         if(choose(nums,left,right,left_ma)>((right-left+1)/2)){
    14.             return left_ma;
    15.         }
    16.         else if(choose(nums,left,right,right_ma)>((right-left+1)/2)){
    17.             return right_ma;
    18.         }
    19.         return -1;
    20.     }
    21.     int choose(vector<int>& nums,int left,int right,int target){
    22.         int count=0;
    23.         for(int i=left;i<=right;i++){
    24.             if(nums[i]==target){
    25.                 count++;
    26.             }
    27.         }
    28.         return count;
    29.     }
    30. };