Create Valid_Parentheses.js

Author: ignacio-chiazzo

LeetcodeProblems/Valid_Parentheses.js

@@ -0,0 +1,67 @@
+/*
+Valid Parentheses
+
+https://leetcode.com/problems/valid-parentheses/description/
+
+Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
+
+An input string is valid if:
+
+Open brackets must be closed by the same type of brackets.
+Open brackets must be closed in the correct order.
+Note that an empty string is also considered valid.
+
+Example 1:
+
+Input: "()"
+Output: true
+Example 2:
+
+Input: "()[]{}"
+Output: true
+Example 3:
+
+Input: "(]"
+Output: false
+Example 4:
+
+Input: "([)]"
+Output: false
+Example 5:
+
+Input: "{[]}"
+Output: true
+*/
+
+var isValid = function(s) {
+  if(s.length === 0)
+    return true;
+  var queue = [];
+  for(var i = 0; i < s.length; i++) {
+    const elem = s[i];
+    if(elem === "(" || elem === "[" || elem === "{") {
+      queue.unshift(elem);
+    } else {
+      if(queue.length === 0)
+          return false;
+      
+      const elemQueue = queue.shift();
+      if(elemQueue === "(" && elem !== ")" ||
+        elemQueue === "[" && elem !== "]" ||
+        elemQueue === "{" && elem !== "}")
+          return false;
+      }
+  }
+  
+  return queue.length === 0;
+};
+
+var main = function(){
+  console.log(isValid(""));
+  console.log(isValid("()"));
+  console.log(isValid("([)]"));
+  console.log(isValid("{[()]}{[()]}"));
+  console.log(isValid("{[())()]}"));
+}
+
+module.exports.main = main