[Leetcode] Simplify Path

class Solution {
public:
string simplifyPath(string path) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
stack<string> stk;
string str = "";

for (int i = 0; i < path.size(); ++i)
{
if (path[i] == '/')
{
if (str == "..")
{
if (!stk.empty()) stk.pop();
}
else if (str != "." && str != "")
{
stk.push(str);
}

str = "";
}
else
{
str += path[i];
}
}

if (str == "..")
{
if (!stk.empty()) stk.pop();
}
else if (str != "." && str != "")
{
stk.push(str);
}

if (stk.empty()) return "/";

string res = "";
while (!stk.empty())
{
res = "/" + stk.top() + res;
stk.pop();
}

return res;
}
};