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

When the test case is "AAACCBB", the set has no majority. Because no element occurs more than 3 times since the length of "AAACCBB" is 7.

Here's the code for "the Boyer and Moore's Linear Time Voting Algorithm":

int Voting(vector &num) {
        int count = 0;
        int candidate;

        for(int i = 0; i < num.size(); ++i) {
            if(count == 0) {
                candidate = num[i];
                count = 1;
            }
            else
                count = (candidate == num[i]) ? ++count : --count;
        }
        return candidate;
    }