Yatra

Author: rahulcode22

BalancedBraces.py

@@ -0,0 +1,45 @@
+class Stack():
+    def __init__(self):
+        self.items = []
+
+    def push(self,item):
+        self.items.append(item)
+
+    def pop(self):
+        if not self.items:
+            return None
+        return self.items.pop()
+
+    def peek(self):
+        if self.items is None:
+            return None
+        return self.items[-1]
+
+    def isEmpty(self):
+        return self.items == []
+
+
+def isBalanced(expression):
+    s = Stack()
+    balanced = True
+    index = 0
+    while index < len(expression) and balanced:
+        symbol = expression[index]
+        if symbol in '({[':
+            s.push(symbol)
+        else:
+            top = s.pop()
+            if not matches(top,symbol):
+                balanced = False
+        index += 1
+    if balanced and s.isEmpty():
+        return True
+    else:
+        return False
+
+def matches(open,close):
+    opens = '[{('
+    closers = ']})'
+    return opens.index(open) == closers.index(close)
+
+print isBalanced('{([])}')