题解 | #压缩牛群编号#

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param chars char字符型vector 
     * @return char字符型vector
     */
    vector<char> compress(vector<char>& chars) {
        // write code here
        vector<char> ans;
        int len = chars.size();
        if (len == 1) return chars;
        int i = 1;
        int left = 0;
        while ( i < len) {
            while (i < len && chars[i] == chars[i-1]) {
               i++; 
            }
            if (i - left > 1) {
                ans.push_back(chars[i-1]);

                int total = i - left;
                vector<char> tmp;
                while (total) {
                    tmp.push_back(total%10 + '0');
                    total /= 10;
                }
                for (int i = tmp.size()-1; i >= 0; i--) {
                    ans.push_back(tmp[i]);
                }
                left = i;
            } else {
                if (chars[i] != chars[i-1] && i > left) {
                    ans.push_back(chars[i-1]);
                    left = i;
                }
                i++;
                //ans.push_back(chars[i]);
            }
        }
        if (chars[i] != chars[i-1] && i > left) {
            ans.push_back(chars[i-1]);
            left = i;
        }
        return ans;
    }
};