leetcode 169

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.

1、常规快排
class Solution {
public:
int majorityElement(vector<int>& nums) {
sort(nums.begin(),nums.end());
return nums[nums.size()/2];
}
};
2、O(n)
class Solution {
public:
int majorityElement(vector<int>& nums) {
int k=0;
int temp;
for(int i=0;i<nums.size();++i){
if(k==0){
temp=nums[i];
k=1;
}
else if(nums[i]==temp){
k++;
}
else
k--;

}
return temp;
}
};