[leetcode] 38. 报数(Java)(字符串处理)

38. 报数

水题

class Solution {
    public String next(String num) {
        String ans = "";
        int i = 0;
        while (i < num.length()) {
            char ch = num.charAt(i);
            int cnt = 0;
            while (i < num.length() && ch == num.charAt(i)) {
                i++;
                cnt++;
            }
            ans += cnt;
            ans += ch;
        }
        return ans;
    }

    public String countAndSay(int n) {
        String num = "1";
        while (--n > 0) {
            num = next(num);
        }
        return num;
    }
}