LeetCode(45) Simplify Path

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题目描述

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

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

本题要求对给定的Unix路径进行简化，关键点在于理解Unix路径的规则以及对一些边界条件要加以考虑。

Unix路径规则：

字符	含义（英文）	含义（中文）
/	root directory	根目录
/	Directory Separator	路径分隔符
.	Current Directory	当前目录
..	Parent Directory	上级目录
~	Home Directory	家目录

Corner Cases:
path = “/../” => 输出 “/”.
连续的多个分隔符 ‘/’ , 例如 “/home//foo/” => 忽略重复的分隔符，输出 “/home/foo”.

解题思路

总体来说本题并不难，只要根据unix path规则，细心考虑可能的边界条件即可。

class Solution {
public:
    string simplifyPath(string path) {
        char slash = '/';
        vector<string> dirs;
        int begin = 0, end = 0;
        int len = path.length();
        while (end < len)
        {
            begin = end;
            while (begin < len && path[begin] == slash)
                begin++;
            end = begin;
            while (end < len && path[end] != slash)
                end++;
            if (begin != end)
            {
                string tmp(path, begin, end - begin);
                if (tmp == ".." && !dirs.empty())
                    dirs.pop_back();
                else if (tmp == ".." && dirs.empty())
                    continue;
                else if (tmp != ".")
                    dirs.push_back(tmp);
            }

        }

        string simplePath = "";
        for (size_t i = 0; i != dirs.size(); ++i)
        {
            simplePath += slash + dirs[i];
        }

        if(dirs.empty())
            simplePath = slash;
        return simplePath;
    }
};