696. Count Binary Substrings

class Solution {
public:
    int countBinarySubstrings(string s) {
        int count=0,size=0;
        char prev=s[0];
        vector<int> group;
        for(auto x:s){
            if(prev==x)
                size++;
            else{
                group.push_back(size);
                prev=x;
                size=1;
            }
        }
        group.push_back(size);
        int len = group.size();
        for(int i=1;i<len;i++){
            count+=min(group[i-1],group[i]);
        }
        return count;
    }
};

class Solution {
public:
    int countBinarySubstrings(string s) {
        int prev=0,cur=1,ans=0;
        int len = s.size();
        for(int i=1;i<len;i++){
            if(s[i-1]!=s[i]){
                ans+=min(prev,cur);
                prev=cur;
                cur=1;
            }
            else
                cur++;
        }
        return ans+min(prev,cur);
    }
};