Check wheather the expression is valid or not Wipro previous year coding question

 

Sample input1:

“(())”

Sample output1:

Valid

Sample input2:

“()(”

Sample output2:

Invalid

Program:

n=input()

list1=list(n)

top=-1

list2=[]

for item in list1:

    if item=='(':

        top+=1

        list2.append(item)

    else:

        list2.pop(top)

        top-=1

if top==-1:

    print("valid")

else:

    print("invalid")