Majority Element(ARRAY-BINARY SEARCH)

QUESTION

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.

FIRST TRY

每找出两个不同的element，则成对删除。最终剩下的一定就是所求的。

class Solution {

public:

    int majorityElement(vector<int> &num) {

        int ret;

        int nTimes = 0;

        for(int i = 0; i < num.size(); i++){

            if(nTimes == 0) 

            {

                ret = num[i];

                nTimes++;

            }

            else if(ret == num[i]) nTimes++;

            else nTimes--; //2 different number, delete

        }

        return ret;

    }

};

Result: Accepted

 

可扩展到⌊ n/k ⌋的情况，每k个不同的element进行成对删除。