括號檢測

def is_valid_parentheses(s):
    stack = []
    mapping = {")": "(", "]": "[", "}": "{"}
    
    for char in s:
        if char in mapping.values(): # 左括號
            stack.append(char)
        elif char in mapping: # 右括號
            if not stack or stack.pop() != mapping[char]:
                return False
    
    return len(stack) == 0