Commit edc952f

@@ -0,0 +1,65 @@
+<<-DOC
+Given an absolute file path (Unix-style), shorten it to the format /<dir1>/<dir2>/<dir3>/....
+
+Here is some info on Unix file system paths:
+
+/ is the root directory; the path should always start with it even if it isn't there in the given path;
+/ is also used as a directory separator; for example, /code/fights denotes a fights subfolder in the code folder in the root directory;
+this also means that // stands for "change the current directory to the current directory"
+. is used to mark the current directory;
+.. is used to mark the parent directory; if the current directory is root already, .. does nothing.
+Example
+
+For path = "/home/a/./x/../b//c/", the output should be
+simplifyPath(path) = "/home/a/b/c".
+
+Here is how this path was simplified:
+* /./ means "move to the current directory" and can be replaced with a single /;
+* /x/../ means "move into directory x and then return back to the parent directory", so it can replaced with a single /;
+* // means "move to the current directory" and can be replaced with a single /.
+
+Input/Output
+
+[time limit] 4000ms (rb)
+[input] string path
+
+A line containing a path presented in Unix style format. All directories in the path are guaranteed to consist only of English letters.
+
+Guaranteed constraints:
+1 ≤ path.length ≤ 5 · 104.
+
+[output] string
+
+The simplified path.
+DOC
+
+describe "simplify_path" do
+  def simplify_path(path)
+    path
+  end
+
+  [
+    { path: "/home/a/./x/../b//c/", x: '/home/a/b/c' },
+    { path: "/a/b/c/../..", x: '/a' },
+    { path: "/../", x: '/' },
+    { path: "/", x: "/" },
+    { path: "//a//b//./././c", x: '/a/b/c' },
+    { path: "a/../../b/", x: '/b' },
+    { path: "a/b/../c/d/../../e/../../", x: "/" },
+    { path: "/.././///", x: "/" },
+    { path: "/cHj/T//", x: "/cHj/T" },
+    { path: "/////..///K/BruP/RMplU/././", x: "/K/BruP/RMplU" },
+    { path: "/mpJN/..///../../ubYgf/tFM/", x: "/ubYgf/tFM" },
+    { path: "/N/cKX/bdrC/./ozFyd/NyuwO/", x: "/N/cKX/bdrC/ozFyd/NyuwO" },
+    { path: "/home/", x: "/home" },
+    { path: "/AagbK/////iavh/M/rmKaS/tXD/././lND//", x: "/AagbK/iavh/M/rmKaS/tXD/lND" },
+    { path: "/oCTY/XJwyB/zA/qgfp/RQFl/kY/./Pa/nth/", x: "/oCTY/XJwyB/zA/qgfp/RQFl/kY/Pa/nth" },
+    { path: "/home//foo/", x: "/home/foo" },
+    { path: "/a/./b/../../c/", x: "/c" },
+    { path: "a/b/../c/d/../../e/../../a/", x: "/a" },
+  ].each do |x|
+    it do
+      expect(simplify_path(x[:path])).to eql(x[:x])
+    end
+  end
+end