Simplify Path

Simplify Path

Given an absolute path for a file (Unix-style), simplify it.

For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"

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".

class Solution {
public:
    string simplifyPath(string path) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        //parse string
        deque<string> layer;
        for(int start=0; start < path.length();){
            if (path[start] == '/'){
                 ++start;
                 continue;                 
            }
            int end = path.find('/',start);
            if (end == string::npos) end = path.length()-1;
            string line(path.substr(start, end-start+1));
            start = end + 1;
            if (line.compare("./")==0 || line.compare(".") == 0) continue;
            else if (line.compare("../")==0 || line.compare("..")==0){
                if (layer.empty()) continue;
                else layer.pop_back();
            }else layer.push_back(line);
        }
        string r("/");
        while(!layer.empty()){
            r += layer.front();
            layer.pop_front();
        }
        if (r.length() > 1 && *r.rbegin()=='/') r.resize(r.length()-1);
        return r;
    }
};