Leetcode 71. Simplify Path

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71. Simplify Path

Total Accepted: 52855 Total Submissions: 238799 Difficulty: Medium

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".

直接上解答：

// http://fisherlei.blogspot.com/2013/01/leetcode-simplify-path.html// 利用栈的特性，如果sub string element// 1. 等于“/”，跳过，直接开始寻找下一个element// 2. 等于“.”，什么都不需要干，直接开始寻找下一个element// 3. 等于“..”，弹出栈顶元素，寻找下一个element// 4. 等于其他，插入当前elemnt为新的栈顶，寻找下一个element// 最后，再根据栈的内容，重新拼path。这样可以避免处理连续多个“/”的问题。public class Solution { // 9ms    public String simplifyPath(String path) {        StringBuilder sb = new StringBuilder();        Stack<String> st = new Stack<String>();        for(int i=1, prev=0; i<= path.length(); i++){ // = to grab the last word            if(i==path.length() || path.charAt(i)=='/'){                String word = path.substring(prev+1, i);                prev = i;                if(word.equals("..")){                    if(!st.isEmpty()) st.pop();                }else if(!word.equals(".") && word.length()>0){ // get rid of //; if . -> no action                    st.push(word);                }            }        }        while(!st.isEmpty()) sb.insert(0, "/"+st.pop());        return sb.length()==0 ? "/":sb.toString();    }}

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