Simplify Path

Author: ignacio-chiazzo

LeetcodeProblems/Simplify_Path.js

@@ -0,0 +1,72 @@
+/*
+Simplify Path
+
+https://leetcode.com/problems/simplify-path/description/
+
+Given an absolute path for a file (Unix-style), simplify it. 
+
+For example,
+path = "/home/", => "/home"
+path = "/a/./b/../../c/", => "/c"
+path = "/a/../../b/../c//.//", => "/c"
+path = "/a//b////c/d//././/..", => "/a/b/c"
+
+In a UNIX-style file system, a period ('.') refers to the current directory, so it can be ignored in a simplified path. Additionally, a double period ("..") moves up a directory, so it cancels out whatever the last directory was. For more information, look here: https://en.wikipedia.org/wiki/Path_(computing)#Unix_style
+
+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".
+*/
+
+var simplifyPath = function(path) {
+  var queue = [];
+  var iter = path.length - 1; 
+  while(iter >= 0) {
+    if(path.charAt(iter) === "/") {
+      iter--;
+    } else if(path.slice(iter - 1, iter + 1) == "/.") {
+       iter -= 2;
+    } else if(path.slice(iter - 2, iter + 1) === "/..") {  
+        iter -= 3;    
+        queue.unshift("/..");
+    } else { // it's a characteriter
+      const endChars = iter;
+      while(iter >= 0 && path.charAt(iter) !== "/") {
+        iter--;
+      }
+      if(queue.length > 0 && queue[0] === "/..") {
+        queue.shift();
+      } else {
+        queue.push("/" + path.slice(iter + 1, endChars + 1));
+      }
+    }
+  }
+  var ret = "";
+    
+  while(queue.length > 0) {
+    elem = queue.shift();
+    if(elem == "/..") {
+      while(queue.length > 0 && queue.shift == "/..") {
+        elem += "/..";
+      }
+      elem = (queue.length > 0) ? elem : "";
+    } else {
+      ret = elem + ret;
+    }
+  }
+  return (ret.length == 0) ? "/" : ret;
+};
+
+var main = function(){
+  console.log(simplifyPath("/../c"));
+  console.log(simplifyPath("/.."));
+  console.log(simplifyPath("/home/")); // => "/home"
+  console.log(simplifyPath("/a/./b/../../c/")); // => "/c"
+  console.log(simplifyPath("/a/../../b/../c//.//")); // => "/c"
+  console.log(simplifyPath("/a//b////c/d//././/..")) // => "/a/b/c"
+}
+
+module.exports.main = main