Update 20-valid-parentheses.js

Author: everthis

20-valid-parentheses.js

@@ -1,3 +1,21 @@
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+ const isValid = function(s) {
+  const stack = []
+  for(let c of s) {
+    if(c === '(') stack.push(')')
+    else if(c === '{') stack.push('}')
+    else if(c === '[') stack.push(']')
+    else if(stack.length === 0 || c !== stack.pop()) return false
+  }
+  return stack.length === 0
+};
+
+
+// another
+
 /**
  * @param {string} s
  * @return {boolean}