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) {
        // write code here
        char[] c = param.toCharArray();
        if(c.length < 2){
            return param;
        }
        StringBuilder sb = new StringBuilder();
        Map<Character, Integer> map = new HashMap<Character, Integer>();
        for (int i = 0; i < c.length; i++) {
            if (map.isEmpty()) {
                map.put(c[i], 1);
            } else if (map.get(c[i]) == null) {
                sb.append(c[i - 1]);
                if (map.get(c[i - 1]) > 1) {
                    sb.append(map.get(c[i - 1]));
                }
                map.clear();
                map.put(c[i], 1);
            } else {
                map.put(c[i], map.get(c[i]) + 1);
            }
        }
        sb.append(c[c.length - 1]);
        if (map.get(c[c.length - 1]) > 1) {
            sb.append(map.get(c[c.length - 1]));
        }
        return sb.toString();
    }
}