[leetcode] Simplify Path

From : https://leetcode.com/problems/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) {
if(path == "") return "";
stack<string> box;
for(int i=0, sz=path.size(); i<sz; i++) {
if(path[i] == '/') continue;
string s;
while(i<sz && path[i] != '/') {
s = s+path[i++];
}
if(s == ".") continue;
else if(s == "..") { if(!box.empty()) box.pop(); }
else box.push(s);
}
string ans;
while(!box.empty()) {
ans = "/"+box.top() + ans;
box.pop();
}
if(ans != "") return ans;
return "/";
}
};