Prefix to infix (expression)

Problem description:

Prefix-to-infix example, with extra parentheses allowed:

* + 4 2 + 3 6 => (4 + 2) * (3 + 6)

-+/3 4 2 5 => (3/4 + 2)-5

-+ 3/4 2 5 => (3 + 4/2)-5

 

Thought 1 (recursion ):

1. Scan from left to right

2. If an operator is encountered, a recursive solution is used to return a new string. If a number is encountered, a numeric string is directly returned. For example:

Case '*':

Return "(" + exp () + "*" + exp () + ")"; // note that brackets are added to ensure that the infix expression can be correctly solved.

Default:

Return next_str;

 

Idea 2 (tree ):

1. Scan from left to right

2. Construct a subtree continuously based on operators

3. traverse the tree in the middle order and output it to obtain the infix expression.

 

Reprinted, please indicate the reference from:

Http://www.cnblogs.com/breakthings/p/4051912.html

Prefix to infix (expression)