這題不難，我用20分鐘搞定了，一次提交通過，比較有成就感：）

public class Solution {

	 public String simplifyPath(String path) {
		 String[] ss = path.split("/");
		 int pos1 = 0;
		 int pos2 = 0;
		 while (pos2 < ss.length) {
			 if (ss[pos2].equals(".")) {
				 pos2++;
			 } else if (ss[pos2].equals("..")) {
				 if (pos1 > 0) {
					 pos1--;
				 }
				 pos2++;
			 } else if (ss[pos2].length() == 0) {
				 pos2++;
			 } else {
				 ss[pos1] = ss[pos2];
				 pos1++;
				 pos2++;
			 }
		 }
		 StringBuilder sb = new StringBuilder();
		 sb.append('/');
		 for (int i = 0; i < pos1; i++) {
			 if (i != 0) {
				 sb.append('/');
			 }
			 sb.append(ss[i]);
		 }
		 return sb.toString();
	}

	public static void main(String[] args) {
		Solution s = new Solution();
		String ss = s.simplifyPath("/a/./b/../../c/.././../../c");
		System.out.println(ss);

	}
}