finish 71

Author: BaffinLee

71. Simplify Path.js

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+/**
+ * 71. Simplify Path
+ * 
+ * Given an absolute path for a file (Unix-style), simplify it.
+ * 
+ * For example,
+ * path = "/home/", => "/home"
+ * path = "/a/./b/../../c/", => "/c"
+ * 
+ * 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".
+ */
+
+/**
+ * @param {string} path
+ * @return {string}
+ */
+var simplifyPath = function(path) {
+	var arr = path.split('/');
+	var stack = [];
+	var len = arr.length;
+	var item = '';
+	for (var i = 0; i < len; i++) {
+			item = arr[i];
+			if (item === '' || item === '.') continue;
+			if (item === '..') {
+					stack.pop();
+			} else {
+					stack.push(item);
+			}
+	}
+	return '/' + stack.join('/');
+};
+
+// 栈