update

src/brackets/index.js

@@ -4,6 +4,28 @@
  * @param {string} str The string of brackets.
  * @returns {"valid" | "invalid"} Whether or not the string is valid.
  */
-function isValid(str) {}
+function isValid(str){
+    let openingBrace = [ '(', '[', '{']
+    let closingBrace = [ ')', ']', '}']
+    let array = []
+    for (let index = 0; index < str.length; index++) {
+        if (openingBrace.includes(str[index])) {
+            array.push(str[index])
+        } 
+        else if (closingBrace.indexOf(str[index]) === openingBrace.indexOf(array[array.length - 1])) {
+            array.pop()
+        } 
+        else{
+          return "invalid"
+
+        } 
+    } 
+    if(array.length === 0){
+      return 'valid'
+    }
+    else{
+      return 'invalid'
+    }
+}
 
 module.exports = isValid;