Count Binary Substrings

Give a string s, count the number of non-empty (contiguous) substrings that have the same number of 0's and 1's, and all the 0's and all the 1's in these substrings are grouped consecutively.

Substrings that occur multiple times are counted the number of times they occur.

Example:

Input: "00110011"
Output: 6

Approach:

C++

#include <bits/stdc++.h>
using namespace std;

int countBinarySubstrings(string s)
{
    //if string is empty then return 0
    if (s.empty())
    {
        return 0;
    }

    bool lastZero = false;
    if (s[0] == '0')
        lastZero = true;

    int zero_count = 0;
    int one_count = 0;
    int count = 0;
    for (int i = 0; i < s.size(); i++)
    {

        //if zero
        if (s[i] == '0')
        {
            //if last zero is false then
            //reset zero count
            if (lastZero == false)
            {
                zero_count = 0;
            }

            //increment zero count
            zero_count++;

            //if one count is greater than 0
            //then decrement one count and update
            //the count
            if (one_count > 0)
            {
                --one_count;
                count++;
            }

            lastZero = true;
        }

        //if one
        else
        {
            if (lastZero == true)
            {
                one_count = 0;
            }
            one_count++;
            if (zero_count)
            {
                --zero_count;
                count++;
            }
            lastZero = false;
        }
    }

    return count;
}

int main()
{
    string str = "00110011";

    cout << countBinarySubstrings(str);

    return 0;
}