题解 | 括号的匹配

import sys
n = int(input())
data = iter(sys.stdin.read().splitlines())
dic ={"{":"}","[":"]","(":")","<":">"}
cmp_key ={"{":"4","[":"3","(":"2","<":"1"}

for _ in range(n):
    flag = True
    stack = []
    s = next(data)
    for c in s:
        if c in cmp_key:  # 左括号判断
            if stack:
                top = stack[-1]  # 直接取栈顶，无需弹出再放回
                if cmp_key[stack[-1]] < cmp_key[c]:
                    flag = False
                    break
            stack.append(c)
        else:  # 右括号
            if not stack:  # 补充：栈空遇到右括号，直接不合法
                flag = False
                break
            if dic[stack.pop()] != c:
                flag = False
                break
    # 统一在循环结束后输出，避免重复打印
    print("YES" if flag and len(stack) == 0 else "NO")