Question

2. Check for balanced parentheses in an expression using a stack. Given the expression string below, examine whether the pairs and the orders of "" "" ""are correct. Show the stack each time it is modified a'(b-c\/[[3-d}"(4+911

Answer 1

1.we will take only the opening and closing brackets in the if condition not the values.To check balanced parentheses in an expression using a stack.  

2.At the end of the string if the stack is empty then it is valid expression.

3.In the below example also we check the stack at the end.

o rnola soli Given Expression string is : T a*(-)/[[3-d]* (4 +9] 61) Note: - & we will read only the opening and the closing I brackets from the string . & If it is opening bracket then push it into stack It, it is closing bracket then check that with the top of the stack. 1 Il closing and and opening bracket is equal, then pop them (closing and opening bracket) Ito the closing and opening bracket is not het lequal then it is invalid expression. check at the end of the string and if the stack is empty then it is valid string. Implementation:- Initially. Empty stack D at(b-c) / [[3-d] * (+9] Steps: – Read the string i n to all pero adwuch push into into stack stack bracket so * opening

Step 2: any bracket Read string until we bind am (6-0) [C344)*(+8)) prical & closing bracket so, check with the element hy which is top of the stack your side Here it is equal so pop them. step-3 Rund string - a*6-1/[[3-2] *ut] - Read string our lituah deli * Empty because wel pop them in Push I' into stack because opening bracket. Read string – a (6-7 / [[3-d] cute step: -4 Push if into stack because opening bracket Read string - at (6-0) / [[3-d] * (utq)] 10.) step 5 & closing bracket so, check the element with the top of the stack * equal o pop it.

step: -6 Read string - a*(6-0 [[[3-d] * Cut 1 ILC * opening ic bracket so push it into stack step-7 Read string – at (6-0) [[3-d] * (u +9) + closing bracket so, check the element with the top of the stack. I go & Here both closing) and opening & brad are equal so pop them step:-3 Rood styrings- a* 6-0 [[3-1]*4+4)] Dell * closing bracket so, check the element with may the top of the stack * Here both are equal so pop them step.-9 we will reach to the end of the string. Find the stack is empty or not. Here it is empty. tao a*(6-9/[[3-d] *U+0] is valid expression