LC439. Ternary Expression Parser - freeCookie🍪 Blog

LC439. Ternary Expression Parser - freeCookie🍪 Blog

LC439. Ternary Expression Parser

Given a string representing arbitrarily nested ternary expressions, calculate the result of the expression. You can always assume that the given expression is valid and only consists of digits 0-9, ?, :, T and F (T and F represent True and False respectively).

Example:

Input: "T?T?F:5:3"    Output: "F"    Explanation: The conditional expressions group right-to-left. Using parenthesis, it is read/evaluated as:                 "(T ? (T ? F : 5) : 3)"                   "(T ? (T ? F : 5) : 3)"            -> "(T ? F : 3)"                 or       -> "(T ? F : 5)"            -> "F"                                    -> "F"  

实现？：这个表达式，记录?和：的位置，利用count找到最外层的表达式，利用recursion一层一层操作。

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