feat: Solve balanced bracket

  - Hackerrank

Author: brianr482

.gitignore

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+.vscode
+.DS_Store

balanced-bracket.js

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+/**
+ * Hackerrank
+ * A bracket is considered to be any one of the following characters: (, ), {,
+ * }, [, or ]. Two brackets are considered to be a matched pair if the an
+ * opening bracket (i.e., (, [, or {) occurs to the left of a closing bracket
+ * (i.e., ), ], or }) of the exact same type. There are three types of matched
+ * pairs of brackets: [], {}, and ().
+ * Given  strings of brackets, determine whether each sequence of brackets is
+ * balanced. If a string is balanced, return YES. Otherwise, return NO.
+ * 
+ * Constraints:
+ * 1. 0 <= n <= 10000
+ * 2. 1 <= |s| <= 10000
+ * 3. All the characters in the sequence: {, }, [, ], (, )
+ * 
+ * This solution got 25 points
+ * Problem link: http://hr.gs/babead
+ */
+
+/**
+ * @param {string} s The string which will be checked
+ * @return {string} 'YES' or 'NO'
+ */
+// Complete the isBalanced function below.
+function isBalanced(s) {
+  // Edge cases 
+  if (s.length === 0 || s.length % 2 === 1) {
+    return 'NO';
+  }
+  const stack = [s.charAt(0)];
+  for (const ch of s.slice(1)) {
+    if (isClose(ch)) {
+      const last = stack.pop();
+      if (!isMatched(last, ch)) {
+        return 'NO';
+      }
+    } else {
+      stack.push(ch);
+    }
+  }
+  return stack.length === 0 ? 'YES' : 'NO';
+}
+
+/**
+ * @param {string} ch - Character to be compared with
+ * @return {boolean}
+ */
+function isClose(ch) {
+  return /\}|\)|\]/i.test(ch);
+}
+
+/**
+ * @param {string} bracket - The first operator
+ * @param {String} next - The next operator
+ * @return {boolean}
+ */
+function isMatched(bracket, next) {
+  switch (bracket) {
+    case '(':
+      return next === ')';
+    case '[':
+      return next === ']';
+    case '{':
+      return next === '}';
+    default:
+      return false;
+  }
+}