IITKESO207A_2P - Calculator

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The input is an arithmetic expression in infix notation, for example, 24 ∗ (3 + 5)/7%3. The problem is to write a program that reads the expression given over multiple lines, parses it, evaluates it and gives the output value as a floating point integer or prints the string “Malformed expression” if the input is malformed. The numbers in the expression are integers but the ouput can be floating point. The operators come from the set {+, −, ∗, /, %,(,)}. The operators act as per their usual definitions. We assume the usual precedence among operators, that is, from lowest to highest, {+, −}, then, *, followed by {/, %} and parenthesis, where, + and binary − are at the same level of precedence and have left to right associativity, so do {/, %}.
Note
The three problems given in the assignments have been merged. 75% of the test cases will check if your code works for problem 1 and 2 and 25% of the test cases will check for problem 3.
Input
The first line contains 'n' , the number of tokens in the expression. 'n' lines follow each containing a either a number or an operator . 
Output
This should be a single number. Errors less than 10^-2 will be ignored. 
Constraints
1<= n <= 20
Inputs will be between -1000 to 1000 
Example
INPUT 1:
4
4
-
-
3
OUTPUT 1:
7
INPUT 2:
7
3
/
(
2
+
1
)
OUTPUT 2:
1
INPUT 3:
3
1
+
(
OUTPUT 3:
Malformed expression

The input is an arithmetic expression in infix notation, for example, 24 ∗ (3 + 5)/7%3. The problem is to write a program that reads the expression given over multiple lines, parses it, evaluates it and gives the output value as a floating point integer or prints the string “Malformed expression” if the input is malformed. The numbers in the expression are integers but the ouput can be floating point. The operators come from the set {+, −, ∗, /, %,(,)}. The operators act as per their usual definitions. We assume the usual precedence among operators, that is, from lowest to highest, {+, −}, then, *, followed by {/, %} and parenthesis, where, + and binary − are at the same level of precedence and have left to right associativity, so do {/, %}.

 

Note

 

The three problems given in the assignment have been merged. 75% of the test cases will check if your code works for problem 1 and 2 and 25% of the test cases will check for problem 3. The result that you will get will be between 0 and 100 , denoting the number of testcases that your code passed. We will consider your maximum score while grading.

 

Update 1: (7 Sep, 2017)

For negative numbers, the '-' and the number will be in separate lines. It is your job to figure out whether it is a unary minus or binary.

Update 2: (13 Sep, 2017 3:15PM)

Earlier you were supposed to print string "Malformed expression" without new line at the end. Sorry, for not being explicit about this fact. But from now onwards, new line at the end of "Malformed expression" won't matter.

 

Input

 

The first line contains 'n' , the number of tokens in the expression. 'n' lines follow each containing a either a number or an operator . 

 

Output

 

This should be a single real number. Errors less than 10^-2 will be ignored. 

 

Constraints

 

1<= n <= 20

 

Inputs will be between -1000 to 1000 

 

Example

 

INPUT 1:

4

4

-

-

3

OUTPUT 1:

7

INPUT 2:

7

3

/

(

2

+

1

)

OUTPUT 2:

1

INPUT 3:

3

1

+

(

OUTPUT 3:

Malformed expression

 


hide comments
ashutoshs25: 2017-09-10 18:45:58

If the output is 7, should it be printed as 7 or 7.000000

Last edit: 2017-09-10 18:46:15
amanyu: 2017-09-10 16:11:46

what should be the value of -4%5.
-4 or 1

harshith_reddy: 2017-09-10 13:26:37

@ubarsaiyan:A very big thank you for mentioning about removing the new line at the end of 'Malformed expression'.

shshnk: 2017-09-10 13:04:02

How would 6/7%4 be interpreted?

Last edit: 2017-09-10 13:05:14
ubarsaiyan: 2017-09-10 12:00:41

@makkarr 25

makkarr: 2017-09-10 01:15:20

how many points are for correctly identifying malformed expression?

bhavy: 2017-09-10 00:04:44

Q1 Is + unary also considered e.g. 2 - + 2 will it be 0 or Malformed expression?
Q2 Is this kind of example also in test case e.g. 1 - - - - 3, - -2?

Last edit: 2017-09-10 00:18:42
ubarsaiyan: 2017-09-09 20:19:19

Please mention that "Malformed expression" has to be printed without a newline character at the end.

suds13: 2017-09-09 18:06:43

@pclubiitk You said "@jyotshak: There will be no unnecessary operators or brackets in the testcases.". Then how is 1---2 even acceptable ?

Programming Club, IITK: 2017-09-09 15:12:07

@nikhilbl: -1
@harshith_reddy: 0.5
@suds13: Take it as -2


Added by:Programming Club, IITK
Date:2017-09-07
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All