1.利用中位数性质

2.哈希表

3.摩尔投票法   与本数相同记为1 不同记为-1

class Solution {
public:
    int majorityElement(vector<int>& nums) {
        int x = 0, votes = 0;
        for(int num : nums){
            if(votes == 0) x = num;
            votes += (num == x ? 1 : -1);
        }
        return x;
    }
};

func majorityElement(nums []int) int {
    flag,ans,tmp:=0,0,0
    for i:=0;i<len(nums);i++{
        if flag==0{
            ans=nums[i]
        }
        if ans==nums[i]{
            tmp=1
        }else{
            tmp=-1
        }
        flag+=tmp
    }
    return ans
}