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Leetcode: Simplify Path

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

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

click to show corner cases.

Corner Cases:

 

  • Did you consider the case where path = "/../"?
    In this case, you should return "/".
  • Another corner case is the path might contain multiple slashes ‘/‘ together, such as "/home//foo/".
    In this case, you should ignore redundant slashes and return "/home/foo".  

分析:细节题。在考虑各cornoer cases的基础上完成所需要求即可。在解此题前要有一个大致的执行逻辑,比如如何执行"."和"..",以及将"filename"还是将"filename/"增加到当前结果中。在下面的代码中,如果是"."我们不做操作;如果是"filename"则将"filename/"加到result末尾;如果是“..”,我们先pop出result末尾的‘/‘(因为我们遇到"filename"是将"filename/"加到result中),然后再将filename从result中pop。这样做逻辑比较清晰,不易出错,刚开始,我的做法是先将"/"加入到result中,然后在分情况处理".",".."以及"filename"的情况,但一直有wrong answer。

class Solution {public:    string simplifyPath(string path) {        string result;        int n = path.length();        //two corner cases        if(n == 0) return result;        if(path == "/../") return "/";        //push root directory        result.push_back(/);        for(int i = 0; i < n;){            while(i < n && path[i] == /)i++;//skip redundant ‘/‘            int j = i;            while(j < n && path[j] != /)j++;//find next ‘/‘                        if(i == n) break;                        string file = path.substr(i,j-i);//get file name            //three cases            if(file == ".."){                if(result != "/"){                    result.pop_back();//pop trailing ‘/‘                    size_t pos = result.find_last_of(/);                    result = result.substr(0,pos+1);                }             }else if(file != "."){                result += file + "/";            }            i = j;        }        if(result.length() > 1 && result.back() == /) result.pop_back();//pop trailing ‘/‘        return result;    }};

 

Leetcode: Simplify Path