https://school.programmers.co.kr/learn/courses/30/lessons/140108
public int solution(String s) {
int answer = 0;
char c = ' ';
int cnt1 =0;
int cnt2 =0;
for(int i=0;i<s.length();i++){
if(cnt1==cnt2) {
answer++;
c=s.charAt(i);
cnt1=0; cnt2=0;
}
if(c == s.charAt(i)) cnt1++;
else cnt2++;
}
return answer;
}