1 Description #
source: https://leetcode.com/problems/simplify-path/
Given a string path
, which is an absolute path (starting with a slash '/'
) to a file or directory in a Unix-style file system, convert it to the simplified canonical path.
In a Unix-style file system, a period '.'
refers to the current directory, a double period '..'
refers to the directory up a level, and any multiple consecutive slashes (i.e. '//'
) are treated as a single slash '/'
. For this problem, any other format of periods such as '...'
are treated as file/directory names.
The canonical path should have the following format:
- The path starts with a single slash
'/'
. - Any two directories are separated by a single slash
'/'
. - The path does not end with a trailing
'/'
. - The path only contains the directories on the path from the root directory to the target file or directory (i.e., no period
'.'
or double period'..'
)
Return the simplified canonical path.
Example 1:
Input: path = "/home/"
Output: "/home"
Explanation: Note that there is no trailing slash after the last directory name.
Example 2:
Input: path = "/../"
Output: "/"
Explanation: Going one level up from the root directory is a no-op, as the root level is the highest level you can go.
Example 3:
Input: path = "/home//foo/"
Output: "/home/foo"
Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.
Constraints:
- 1 <= path.length <= 3000
path
consists of English letters, digits, period'.'
, slash'/'
or'_'
.path
is a valid absolute Unix path.
2 Solution #
#include <vector>
#include <sstream>
class Solution {
public:
string simplifyPath(string path) {
// Space complexity: O(D), D is the depth of path.
// Time complexity: O(D), D is the depth of path.
std::istringstream is(path);
std::string token;
std::vector<std::string> result{"/"};
while(std::getline(is, token, '/')){
if(token == ""){
continue;
}
if(result.back() != "/"){
result.push_back("/");
}
if(token == ".."){
int pop_times = 0;
while(result.size() > 1 && pop_times < 3){
result.pop_back();
pop_times++;
}
}else if(token == "."){
if(result.size() > 1){
result.pop_back();
}
}else{
result.push_back(token);
}
}
std::stringstream ss;
for(const auto& path: result){
ss << path;
}
return ss.str();
}
};