Re: [閒聊] 每日leetcode

[dont (dont)]

1106. Parsing A Boolean Expression

## 思路

掃字串存Stack

1. 如果ch是')' 就pop stack直到'(' 並記錄目前的true/false
然後根據operator (!, &, |)運算把結果丟回Stack
2. 如果ch是','跳過, 其餘丟Stack

## Code

```python
class Solution:
    def parseBoolExpr(self, expression: str) -> bool:

        stack = []
        for ch in expression:
            if ch == ')':
                has_true = has_false = False
                while stack[-1] != '(':
                    prev = stack.pop()
                    if prev == 't':
                        has_true = True
                    else:
                        has_false = True
                stack.pop()  # (

                op = stack.pop()  # & | !
                if op == '!':
                    res = not has_true
                elif op == '&':
                    res = not has_false
                else:
                    res = has_true

                stack.append('t' if res else 'f')

            elif ch != ',':
                stack.append(ch)

        return stack[-1] == 't'
```

--
https://i.imgur.com/kyBhy6o.jpeg

--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 185.213.82.84 (臺灣)
※ 文章網址: https://www.ptt.cc/bbs/Marginalman/M.1729387752.A.20C.html
→ sustainer123: 大師