Merge pull request #1 from doms/balanced-brackets

implement balanced brackets in python

Python/balanced-brackets.py

@@ -0,0 +1,21 @@
+PAIRINGS = {
+    '(': ')',
+    '{': '}',
+    '[': ']'
+}
+
+
+def is_balanced(symbols):
+    stack = []
+    for s in symbols:
+        if s in PAIRINGS.keys():
+            stack.append(s)
+        else:
+            try:
+                expected_opening_symbol = stack.pop()
+            except IndexError:  # too many closing symbols
+                return False
+            if s != PAIRINGS[expected_opening_symbol]:  # mismatch
+                return False
+    return len(stack) == 0  # false if too many opening symbols
+