Classic Interview 150 Questions P71 Simplify Path

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Timeline

Timeline

2025-11-18

init

Stack

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Problem:

P71 Simplify Path

https://leetcode.cn/problems/simplify-path/description/?envType=study-plan-v2&envId=top-interview-150

We need to distinguish between the first “/” and the subsequent "/"s. The first is the root directory, while the subsequent ones are separators. Therefore, we can treat a directory as “/” + “directory name”.

If the directory is “”, i.e., an empty string, then it is the root directory.

#include <string>
#include <stack>
#include <sstream>
using std::string;
using std::stringstream;
using std::stack;

class Solution {
    public:
	string simplifyPath(string path)
	{
		string res, curr;
		stringstream ss(path);
		stack<string> st;
		while (std::getline(ss, curr, '/')) {
			if (curr.empty())
				continue;
			if (curr.compare("..") == 0) {
				if (!st.empty())
					st.pop();
				else
					continue;
			} else if (curr.compare(".") == 0) {
				continue;
			} else {
				st.push(curr);
			}
		}
		while (!st.empty()) {
			curr = st.top();
			st.pop();
			res.insert(0, curr);
			res.insert(0, "/");
		}
		if (res.empty())
			res = "/";		
		return res;
	}
};