剑指Offer27 数组中超过一半的数

/*************************************************************************
    > File Name: 27_MoreThanHalfNum.c
    > Author: Juntaran
    > Mail: JuntaranMail@gmail.com
    > Created Time: 2016年08月31日 星期三 16时40分55秒
 ************************************************************************/

#include <stdio.h>

int FindNum(int* nums, int length)
{
    if (nums==NULL || length<=0)
        return -1;
    
    int ret = nums[0];
    int count = 1;
    for (int i = 0; i < length; ++i)
    {
        if (nums[i] == ret)
            count ++;
        else
            count --;
        if (count == 0)
        {
            ret = nums[i];
            count = 1;
        }
    }
    
    // 检验是否正确
    int count2 = 0;
    for (int i = 0; i < length; ++i)
    {
        if (nums[i] == ret)
            count2 ++;
    }
    if (count2*2 > length)
        return ret;
    else
        return -1;
}

int main()
{
    int nums[] = {1,2,3,2,2,2,5,4,2};
    int length = 9;
    int ret = FindNum(nums, length);
    if (ret == -1)
        printf("Not Find
");
    else
        printf("ret is %d
", ret);
    
    return 0;
}