[leetcode]482. License Key Formatting

[leetcode]482. License Key Formatting

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Analysis

生而为人要善良啊~—— [ummmm~]

You are given a license key represented as a string S which consists only alphanumeric character and dashes. The string is separated into N+1 groups by N dashes.
Given a number K, we would want to reformat the strings such that each group contains exactly K characters, except for the first group which could be shorter than K, but still must contain at least one character. Furthermore, there must be a dash inserted between two groups and all lowercase letters should be converted to uppercase.
Given a non-empty string S and a number K, format the string according to the rules described above.
按照他的意思对字符串进行操作就行了，注意把字母都转换成大写的。

Implement

class Solution {
public:
    string licenseKeyFormatting(string S, int K) {
        string tmp = "";
        for(auto s:S){
            if(isalpha(s))
                tmp += toupper(s);
            if(isdigit(s))
                tmp += s;
        }
        string res = "";
        int len = tmp.length();
        if(len%K == 0){
            int i = 0;
            int cnt = 0;
            while(i<len){
                if(cnt == K){
                    res += '-';
                    cnt = 0;
                }
                res += tmp[i];
                cnt++;
                i++;
            }
        }
        else{
            int t = len%K;
            res += tmp.substr(0, t);
            int i = t;
            int cnt = K;
            while(i<len){
                if(cnt == K){
                    res += '-';
                    cnt = 0;
                }
                res += tmp[i];
                cnt++;
                i++;
            }
        }
        return res;
    }
};