71. Simplify Path(M)

71. 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".

 

class Solution {
public:
     string simplifyPath(string path) {
        deque<string> qs;
        string result;
        int plen = path.size();
        string::size_type curindex = 0, lastindex = 0;

        while (lastindex < plen && (curindex = path.find("/", lastindex)) != string::npos)
        {
            if(path.find("//", lastindex))
            {
                qs.push_back(path.substr(lastindex, curindex+1-lastindex));
                lastindex = curindex+2;
            }else if (path.find("./", lastindex)) {
                lastindex = curindex+1;
            }else if (path.find(".//", lastindex)) {
                lastindex = curindex+2;
            }else if (path.find("../", lastindex)) {
                qs.pop_back(); // go back one step
                lastindex = curindex+1;
            }else if (path.find("..//", lastindex)) {
                qs.pop_back();
                lastindex = curindex+2;
            }else {
                qs.push_back(path.substr(lastindex, curindex+1-lastindex));
                lastindex = curindex+1;
            }
        }

        while (!qs.empty()) {
            string tmp = qs.front();
            qs.pop_front();
            result.append(tmp);
        }
        if(result.size() != 1){
            result.resize(result.size()-1);
        }
        return result;
    }
};