【LeetCode】Simplify Path 解题报告

【题目】

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".

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  Stack String

【解析】

用过Linux的人都应该熟悉这个，不过其中需要注意的是 /../ 的结果是 / ，也就是说根目录的上层目录还是根目录。

【Java代码】

public class Solution {
    public String simplifyPath(String path) {
        Stack stack = new Stack();
        
        int len = path.length();
        int start = 0;
        int i = 0;
        
        while (i < len) {
            while (i < len && path.charAt(i) == '/') {
                i++;
            }
            
            start = i;
            while (i < len && path.charAt(i) != '/') {
                i++;
            }
            
            if (i > start) {
                String part = path.substring(start, i);
                
                if (part.equals("..")) {
                    if (!stack.isEmpty()) stack.pop();
                } else if (!part.equals(".")) {
                    stack.push(part);
                }
            }
        }
        
        if (stack.isEmpty()) {
            return "/";
        }
        
        String res = "";
        while (!stack.isEmpty()) {
            res = "/" + stack.pop() + res;
        }
        
        return res;
    }
}