hackerrank-balanced-brackets.py

def isBalanced(s):
    stack = [s[0]]
    for c in s[1:]:
        if len(stack) == 0:
            stack.append(c)
        elif (c == ")" and stack[-1] == "(") or (c == "}" and stack[-1] == "{") or (c == "]" and stack[-1] == "["):
                stack.pop()
        else:
            stack.append(c)
    return "YES" if len(stack) == 0 else "NO"