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Return the result of evaluating a given boolean expression
, represented as a string.
An expression can either be:
"t"
, evaluating to True
;
"f"
, evaluating to False
;
"!(expr)"
, evaluating to the logical NOT of the inner expression expr
;
"&(expr1,expr2,...)"
, evaluating to the logical AND of 2 or more inner expressions expr1, expr2, ...
;
"|(expr1,expr2,...)"
, evaluating to the logical OR of 2 or more inner expressions expr1, expr2, ...
Example 1:
Input: expression = "!(f)"
Output: true
Example 2:
Input: expression = "|(f,t)"
Output: true
Example 3:
Input: expression = "&(t,f)"
Output: false
Example 4:
Input: expression = "|(&(t,f,t),!(t))"
Output: false
Constraints:
1 <= expression.length <= 20000
expression[i]
consists of characters in {'(', ')', '&', '|', '!', 't', 'f', ','}
.
expression
is a valid expression representing a boolean, as given in the description.
[String]
Hints
Hint 1
Write a function "parse" which calls helper functions "parse_or", "parse_and", "parse_not".