2021.10.4打卡

思路：模拟

class Solution {
public:
    string licenseKeyFormatting(string s, int k) {
        string ans;
        int cnt=0;
        for(int i=s.size()-1;i>=0;--i){
            if(s[i]!='-'){
                cnt++;
                ans.push_back(toupper(s[i]));
                if(cnt%k==0)
                    ans.push_back('-');
            }
        }

        if(ans.size()&&ans.back()=='-')
            ans.pop_back();

        reverse(ans.begin(),ans.end());
        
        return ans;
    }
};