CODE 61. Simplify Path

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版权声明：本文为博主原创文章，转载请注明出处：http://blog.jerkybible.com/2013/10/06/2013-10-06-CODE 61 Simplify Path/

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Given an absolute path for a file (Unix-style), simplify it.
For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"

click to show corner cases.
Corner Cases:

• Did you consider the case where path = "/../"?
  In this case, you should return "/".
• Another corner case is the path might contain multiple slashes '/' together,
  such as "/home//foo/".
  In this case, you should ignore redundant slashes and return "/home/foo".

public String simplifyPath(String path) {
	// Start typing your Java solution below
	// DO NOT write main() function
	if (null == path || "".equals(path) || !path.startsWith("/")) {
		return "";
	}

	List<String> pathList = new ArrayList<String>();
	char[] paths = path.toCharArray();
	StringBuilder sb = new StringBuilder();
	for (int i = 0; i < paths.length; i++) {
		if (paths[i] == '/') {
			if (!sb.toString().equals("")) {
				if (!sb.toString().equals(".")
						&& !sb.toString().equals("..")) {
					pathList.add(sb.toString());
				} else if (sb.toString().equals("..")) {
					if (!pathList.isEmpty()) {
						pathList.remove(pathList.size() - 1);
					}
				}
				sb = null;
				sb = new StringBuilder();
			}
		} else {
			sb.append(paths[i]);
		}
	}
	if (!sb.toString().equals("")) {
		if (!sb.toString().equals(".") && !sb.toString().equals("..")) {
			pathList.add(sb.toString());
		} else if (sb.toString().equals("..")) {
			if (!pathList.isEmpty()) {
				pathList.remove(pathList.size() - 1);
			}
		}
	}
	if (pathList.isEmpty()) {
		return "/";
	} else {
		sb = null;
		sb = new StringBuilder();
		for (String s : pathList) {
			sb.append("/" + s);
		}
		return sb.toString();
	}
}