第25题 Simplify Path

最新推荐文章于 2024-11-03 17:30:00 发布

amberFeb

最新推荐文章于 2024-11-03 17:30:00 发布

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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".

Solution in Java:

public class Solution {
    public String simplifyPath(String path) {
        String[] paths = path.split("/+");
        Stack<String> spath = new Stack<String>();
      
        for(int i=0; i<paths.length; i++){
            if(!paths[i].equals("")&&!paths[i].equals(".")) spath.push(paths[i]);
        }
       
        String simPath="";
        int back=0;
        while(!spath.empty()){
            String cur = spath.pop();
            if(cur.equals(".."))    back++;
            else if(back>0) back--;
            else{
                simPath= "/" + cur + simPath;
            }
        }
        if(simPath.equals("")) simPath="/";
        return simPath;
    }
}

Note: Java字符串比较要用equals()函数哦。String分割有函数split()。Java中Stack的pop()函数会返回栈顶对象并且将对象pop出来。

Solution in c++:

class Solution {
public:
    string simplifyPath(string path) {
        int length = path.length();
        int start=0, index=0;
        stack<string> paths;
        while(index<length){
            if(path[start]=='/')    {
                start++;
                index++;
            }
            else if(path[index]=='/'){
                string curPath = path.substr(start, index-start);
                if(!(curPath==".")){
                    paths.push(curPath);
                }
                start=index+1;
                index=start;  
            }
            else{
                index++;
            }
        }
        if(start!=length){
            string curPath = path.substr(start);
            if(!(curPath==".")) paths.push(curPath);
        }
        int back=0;
        string simPath="";
        while(!paths.empty()){
            string curPath=paths.top();
            paths.pop();
            if(curPath=="..")   back++;
            else if(back>0) back--;
            else  simPath= "/"+curPath +simPath;
        }
        if(simPath=="") simPath="/";
        return simPath;
    }
};

Note：C++的string没有split函数可用，需要自己实现。C++中字符串可以用"=="比较。C++中的stack类pop()函数return值为void，即只pop栈顶元素，不返回该对象的值。想要获取栈顶元素值，要先用top()元素获取元素值，再pop()。在java中与top()对等的函数是peak()。