Linear Time Voting Algorithm. I don't get it

Question

As I was reading this (Find the most common entry in an array), the Boyer and Moore\'s Linear Time Voting Algorithm was suggested.

If you follow the link to the si

Answer 1

I wrote a C++ code for this algorithm

char find_more_than_half_shown_number(char* arr, int len){
int i=0;
std::vector vec;
while(i=(len+1)/2)
    return vec[0];
else
    return -1;
}

and the main function is as below:

int main(int argc, const char * argv[])
{
    char arr[]={'A','A','A','C','C','B','B','C','C','C','B','C','C'};
    int len=sizeof(arr)/sizeof(char);
    char rest_num=find_more_than_half_shown_number(arr,len);
    std::cout << "rest_num="<