Leetcode: Simplify Path

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".

string simplifyPath(string path) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        assert(path[0]=='/');
		vector<string> vec;
		int i = 0;
		while(i < path.size())
		{
			int end = i+1;
			while(end < path.size() && path[end] != '/')
				end++;
			string sub = path.substr(i+1,end-i-1);
			if(sub.length()>0){
				if(sub == ".."){
					if(!vec.empty()) vec.pop_back();
				}
				else if(sub != ".")
					vec.push_back(sub);
			}
			i=end;
		}
		if(vec.empty())return "/";
		string res;
		for(int i = 0; i< vec.size(); i++)
			res += "/" + vec[i];
		return res;
    }