leetcode

0 class Solution {

1 public:

2 bool parseBoolExpr(const string &expression) const {

3 bool state = false;

4 stack<char> op;

5

6 const auto flush = [&](int &i) {

7 for (int count = 0; i < size(expression); i++) {

8 if (expression[i] == '(')

9 count++;

10 else if (expression[i] == ')' && count-- == 0)

11 break;

12 }

13 op.pop();

14 };

15

16 for (int i = 0; i < size(expression); i++) {

17 switch (expression[i]) {

18 case 't': state = true; break;

19 case 'f': state = false; break;

20 case '!':

21 case '&':

22 case '|': op.push(expression[i]); break;

23 case ',':

24 // lazy evaluation

25 switch (op.top()) {

26 case '&':

27 if (!state) flush(i);

28 break;

29 case '|':

30 if (state) flush(i);

31 break;

32 }

33 break;

34 case ')':

35 if (op.top() == '!') state = !state;

36

37 op.pop();

38 break;

39 }

40 }

41

42 return state;

43 }

44 };