[codility]Dominator

最新推荐文章于 2018-04-22 19:15:58 发布

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本文介绍了一种寻找数组中主导元素的方法，主导元素是指出现次数超过数组长度一半的元素。通过遍历数组并使用计数的方式记录潜在主导元素，再验证该元素是否真正为主导元素。

// you can also use includes, for example:
// #include <algorithm>
int solution(const vector<int> &A) {
    // write your code in C++98
    //...record the count of current winner number, then
    int winnerNumber;
    int winnerNumberLeftCount = 0;
    for(int i = 0; i < A.size(); ++i)
    {
        if(winnerNumberLeftCount == 0)
        {
            winnerNumber = A[i];
            winnerNumberLeftCount++; 
        }
        else
        {
            if(winnerNumber == A[i]) winnerNumberLeftCount++;
            else winnerNumberLeftCount--;
        }
    }
    //...enumetate the array and count the occurence of this winner number, 
    if(winnerNumberLeftCount <= 0) return -1;
    int winnerNumberRealCnt = 0;
    int index;
    for(int i = 0; i < A.size(); ++i)
    {
        if(A[i] == winnerNumber) 
        {
            winnerNumberRealCnt++;
            index = i;
        }
    }
    //...if the last winner number is not the dominator then return -1
    if(winnerNumberRealCnt <= (int)A.size()/2) return -1;
    else return index;
}