1. 概述

以 Unix 风格给出一个文件的绝对路径，将其转换为规范路径。

输入：”/a/./b/../../c/“ 输出：”/c”

2. 解题

<?php
class Solution {
    /**
     * @param String $path
     * @return String
     */
    public function simplifyPath($path) {
        $elements = explode('/', $path);
        if (!$elements) {
            return '';
        }
        $stack = new SplStack();
        foreach ($elements as $v) {
            if (!$v || $v == '.') {
                continue;
            }
            if ($v == '..') {
                if ($stack->isEmpty()) {
                    return '';
                }
                $stack->pop();
            } else {
                $stack->push($v);
            }
        }
        $ret = '';
        while (!$stack->isEmpty()) {
            $ret = '/' . $stack->pop();
        }
        return $ret ?: '/';
    }
}
$path = "/a/./b/../../c/";
$cls = new Solution();
$r = $cls->simplifyPath($path);
echo $r;