2016 Update

Task/Balanced-brackets/JavaScript/balanced-brackets-1.js

@@ -1,43 +1,17 @@
-function createRandomBracketSequence(maxlen)
-{
-   var chars = { '0' : '[' , '1' : ']' };
-   function getRandomInteger(to)
-   {
-      return Math.floor(Math.random() * (to+1));
-   }
-   var n = getRandomInteger(maxlen);
-   var result = [];
-   for(var i = 0; i < n; i++)
-   {
-     result.push(chars[getRandomInteger(1)]);
-   }
-   return result.join("");
+function shuffle(str) {
+  var a = str.split(''), b, c = a.length, d
+  while (c) b = Math.random() * c-- | 0, d = a[c], a[c] = a[b], a[b] = d
+  return a.join('')
 }
 
-function bracketsAreBalanced(s)
-{
-  var open = (arguments.length > 1) ? arguments[1] : '[';
-  var close = (arguments.length > 2) ? arguments[2] : ']';
-  var c = 0;
-  for(var i = 0; i < s.length; i++)
-  {
-    var ch = s.charAt(i);
-    if ( ch == open )
-    {
-      c++;
-    }
-    else if ( ch == close )
-    {
-      c--;
-      if ( c < 0 ) return false;
-    }
-  }
-  return c == 0;
+function isBalanced(str) {
+  var a = str, b
+  do { b = a, a = a.replace(/\[\]/g, '') } while (a != b)
+  return !a
 }
 
-var c = 0;
-while ( c < 5 ) {
-  var seq = createRandomBracketSequence(8);
-  alert(seq + ':\t' + bracketsAreBalanced(seq));
-  c++;
+var M = 20
+while (M-- > 0) {
+  var N = Math.random() * 10 | 0, bs = shuffle('['.repeat(N) + ']'.repeat(N))
+  console.log('"' + bs + '" is ' + (isBalanced(bs) ? '' : 'un') + 'balanced')
 }