Add valid parentheses

Author: dwqs

codewars/201807/valid-parentheses.md

@@ -0,0 +1,78 @@
+
+## Description
+
+Write a function called that takes a string of parentheses, and determines if the order of the parentheses is valid. The function should return `true` if the string is valid, and `false` if it's invalid.
+
+### Examples
+```js
+"()" => true
+")(()))" => false
+"(" => false
+"(())((()())())" => true
+```
+
+**Kata's link**: [Valid Parentheses](https://www.codewars.com/kata/valid-parentheses)
+
+## Best Practices
+
+**First:**
+```js
+// I had something that was smaller and looked cooler, but
+// this is how you'd want to write an actual parser.
+function validParentheses(string){
+ var tokenizer = /[()]/g, // ignores characters in between; parentheses are
+ count = 0, // pretty useless if they're not grouping *something*
+ token;
+ while(token = tokenizer.exec(string), token !== null){
+ if(token == "(") {
+ count++;
+ } else if(token == ")") {
+ count--;
+ if(count < 0) {
+ return false;
+ }
+ }
+ }
+ return count == 0;
+}
+```
+
+**Second:**
+```js
+function validParentheses(parens){
+ var indent = 0;
+ 
+ for (var i = 0 ; i < parens.length && indent >= 0; i++) {
+ indent += (parens[i] == '(') ? 1 : -1; 
+ }
+ 
+ return (indent == 0);
+}
+```
+
+**Third:**
+```js
+function validParentheses(parens){
+ var n = 0;
+ for (var i = 0; i < parens.length; i++) {
+ if (parens[i] == '(') n++;
+ if (parens[i] == ')') n--;
+ if (n < 0) return false;
+ }
+ 
+ return n == 0;
+}
+```
+
+## My solutions
+```js
+function validParentheses(parens){
+ //TODO 
+ const reg = /\(\)/g;
+ while(reg.test(parens)) {
+ parens = parens.replace(reg, '');
+ }
+ 
+ return parens === '';
+}
+```

readme.md

@@ -15,6 +15,7 @@ Here is my codewars homepage: https://www.codewars.com/users/dwqs.
 * [Sometimes](codewars/201512/sometimes.md)
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-* [Regex Password Validation](codewars/201702/regex-password-validation.md)
+* [Regex Password Validation](codewars/git/regex-password-validation.md)
 * [Find Unique Number](codewars/201701/find-unique-number.md)
+* [Valid Parentheses](codewars/201807/valid-parentheses.md)