leetcode 71 Simplify Path

题目连接

https://leetcode.com/problems/simplify-path/ 

Simplify Path

Description

Given an absolute path for a file (Unix-style), simplify it.

For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"

简化linux文件路径,”.”代表当前目录,”..”代表上级目录 
大体做法:先把path按’/’符分割保存起来(由于c++ string没有split函数,自己写一个吧) 
再把切割后的字符串扫一遍即可。 
具体如下

class Solution {
public:
    string simplifyPath(string path) {
        string ans;
        if(path.empty()) return ans;
        auto split = [=](char sep = '/')->vector<string> {
            string temp;
            vector<string> res;
            size_t start = 0, end = 0;
            while((end = path.find(sep, start)) != string::npos) {
                temp = path.substr(start, end - start);
                if(temp != "") res.emplace_back(temp);
                start = end + 1;
            }
            temp = path.substr(start);
            if(temp != "") res.emplace_back(temp);
            return res;
        };
        vector<string> res = split();
        vector<string> stk;
        for(auto &r: res) {
            if(r ==".") continue;
            else if(r == "..") {
                if(!stk.empty()) stk.pop_back();
            } else {
                stk.push_back(r);
            }
        }
        if(stk.empty()) {
            ans.push_back('/');
        } else {
            for(auto &r: stk) {
                ans.push_back('/');
                ans += r;
            }
        }
        return ans;
    }
};