Parsing A Boolean Expression

class Solution {
public:
    bool parseBoolExpr(string expression) {
        stack<char> st;
        for (char c : expression) {
            if (c == ',') continue;
            if (c != ')') { st.push(c); continue; }
            int t = 0, f = 0;
            while (st.top() != '(') {
                char x = st.top(); st.pop();
                if (x == 't') ++t;
                else ++f;
            }
            st.pop(); // '('
            char op = st.top(); st.pop();
            bool val;
            if (op == '!') val = (t == 0);
            else if (op == '&') val = (f == 0);
            else val = (t > 0);
            st.push(val ? 't' : 'f');
        }
        return st.top() == 't';
    }
};

func parseBoolExpr(expression string) bool {
    st := []byte{}
    for i := 0; i < len(expression); i++ {
        c := expression[i]
        if c == ',' {
            continue
        }
        if c != ')' {
            st = append(st, c)
            continue
        }
        t, f := 0, 0
        for st[len(st)-1] != '(' {
            x := st[len(st)-1]
            st = st[:len(st)-1]
            if x == 't' {
                t++
            } else {
                f++
            }
        }
        st = st[:len(st)-1] // '('
        op := st[len(st)-1]
        st = st[:len(st)-1]
        var val bool
        switch op {
        case '!':
            val = t == 0
        case '&':
            val = f == 0
        default:
            val = t > 0
        }
        if val {
            st = append(st, 't')
        } else {
            st = append(st, 'f')
        }
    }
    return st[len(st)-1] == 't'
}

class Solution:
    def parseBoolExpr(self, expression: str) -> bool:
        st: List[str] = []
        for c in expression:
            if c == ',':
                continue
            if c != ')':
                st.append(c)
                continue
            t = f = 0
            while st[-1] != '(':
                x = st.pop()
                if x == 't':
                    t += 1
                else:
                    f += 1
            st.pop()  # '('
            op = st.pop()
            if op == '!':
                val = t == 0
            elif op == '&':
                val = f == 0
            else:
                val = t > 0
            st.append('t' if val else 'f')
        return st[-1] == 't'

function parseBoolExpr(expression) {
    const st = [];
    for (const c of expression) {
        if (c === ',') continue;
        if (c !== ')') {
            st.push(c);
            continue;
        }
        let t = 0, f = 0;
        while (st[st.length - 1] !== '(') {
            const x = st.pop();
            if (x === 't') t++;
            else f++;
        }
        st.pop(); // '('
        const op = st.pop();
        let val;
        if (op === '!') val = t === 0;
        else if (op === '&') val = f === 0;
        else val = t > 0;
        st.push(val ? 't' : 'f');
    }
    return st[st.length - 1] === 't';
}

class Solution {
    public boolean parseBoolExpr(String expression) {
        Deque<Character> st = new ArrayDeque<>();
        for (int i = 0; i < expression.length(); i++) {
            char c = expression.charAt(i);
            if (c == ',') continue;
            if (c != ')') {
                st.push(c);
                continue;
            }
            int t = 0, f = 0;
            while (st.peek() != '(') {
                char x = st.pop();
                if (x == 't') t++;
                else f++;
            }
            st.pop(); // '('
            char op = st.pop();
            boolean val;
            if (op == '!') val = t == 0;
            else if (op == '&') val = f == 0;
            else val = t > 0;
            st.push(val ? 't' : 'f');
        }
        return st.peek() == 't';
    }
}

function parseBoolExpr(expression: string): boolean {
    const st: string[] = [];
    for (const c of expression) {
        if (c === ',') continue;
        if (c !== ')') {
            st.push(c);
            continue;
        }
        let t = 0, f = 0;
        while (st[st.length - 1] !== '(') {
            const x = st.pop();
            if (x === 't') t++;
            else f++;
        }
        st.pop(); // '('
        const op = st.pop();
        let val: boolean;
        if (op === '!') val = t === 0;
        else if (op === '&') val = f === 0;
        else val = t > 0;
        st.push(val ? 't' : 'f');
    }
    return st[st.length - 1] === 't';
}