1106. 解析布尔表达式

1106. 解析布尔表达式

class Solution {
    int index;
    char[] ch;
     public boolean parseBoolExpr(String expression) {
        ch = expression.toCharArray();
        index = 0;
        return dfs();
    }

    public boolean dfs() {
        if (ch[index] == 'f') {
            index++;
            return false;
        }
        if (ch[index] == 't') {
            index++;
            return true;
        }
        char op = ch[index];
        index += 2;

        boolean res = true;
        if (op == '|') res = false;

        while(ch[index] != ')') {
            if (ch[index] == ',') {
                index ++;
            } else {
                boolean nextBool = dfs();
                if (op == '|') {
                    res = res | nextBool;
                } else {
                    res = res & nextBool;
                }
            }
        }
        index ++;
        if (op == '!') {
            res = !res;
        }
        return res;
    }
}