Prefix to Infix Conversion

Infix : An expression is called the Infix expression if the operator appears in between the operands in the expression. Simply of the form (operand1 operator operand2). 
Example : (A+B) * (C-D)

Prefix : An expression is called the prefix expression if the operator appears in the expression before the operands. Simply of the form (operator operand1 operand2). 
Example : *+AB-CD (Infix : (A+B) * (C-D) )

Given a Prefix expression, convert it into a Infix expression. 
Computers usually does the computation in either prefix or postfix (usually postfix). But for humans, its easier to understand an Infix expression rather than a prefix. Hence conversion is need for human understanding.

Examples: 

Input : Prefix : *+AB-CD
Output : Infix : ((A+B)*(C-D))

Input : Prefix : *-A/BC-/AKL
Output : Infix : ((A-(B/C))*((A/K)-L))

Algorithm for Prefix to Infix: 

• Read the Prefix expression in reverse order (from right to left)
• If the symbol is an operand, then push it onto the Stack
• If the symbol is an operator, then pop two operands from the Stack 
  Create a string by concatenating the two operands and the operator between them. 
  string = (operand1 + operator + operand2)
  And push the resultant string back to Stack
• Repeat the above steps until the end of Prefix expression.
• At the end stack will have only 1 string i.e resultant string

Implementation:

Infix : ((A-(B/C))*((A/K)-L))

Time Complexity:O(n)
Auxiliary Space: O(n)