题解 | #压缩字符串(一)#

import java.util.*;


public class Solution {
    /**
     * 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 param string字符串 
     * @return string字符串
     */
    public String compressString (String param) {
        int n = param.length();
        StringBuilder ans = new StringBuilder();
        for (int l = 0, r = 1; l < n; l = r, r = l + 1) {
            while (r < n && param.charAt(l) == param.charAt(r)) r++;
            ans.append(param.charAt(l));
            if (r > l + 1) ans.append(r - l);
        }
        return ans.toString();
    }
}