r/dailyprogrammer Challenge #298 [Easy] Solution

dailyprog298e.py

exp = raw_input()

# assuming exp is balanced

stack = []
justClosed = False # did we just close a paren in the last operation

for ch in exp:
    if ch != ')':
        stack.append(ch)
        justClosed = False
    else:
        poppedItems = []
        lastItem = stack.pop()
        while lastItem != '(':
            poppedItems.append(lastItem)
            lastItem = stack.pop()
        if justClosed == True and len(poppedItems) == 1:
            stack.append(poppedItems[0])
        elif len(poppedItems) == 0:
            pass # put nothing to the stack
        else:
            poppedItems.reverse()
            stack.append('(' + ''.join(poppedItems) + ')')
        justClosed = True

print ''.join(stack)