 # AlKYala's solution

## to Wordy in the Java Track

Published at Oct 03 2019 · 0 comments
Instructions
Test suite
Solution

Parse and evaluate simple math word problems returning the answer as an integer.

## Iteration 0 — Numbers

Problems with no operations simply evaluate to the number given.

What is 5?

Evaluates to 5.

What is 5 plus 13?

Evaluates to 18.

Handle large numbers and negative numbers.

## Iteration 2 — Subtraction, Multiplication and Division

Now, perform the other three operations.

What is 7 minus 5?

2

What is 6 multiplied by 4?

24

What is 25 divided by 5?

5

## Iteration 3 — Multiple Operations

Handle a set of operations, in sequence.

Since these are verbal word problems, evaluate the expression from left-to-right, ignoring the typical order of operations.

What is 5 plus 13 plus 6?

24

What is 3 plus 2 multiplied by 3?

15 (i.e. not 9)

## Iteration 4 — Errors

The parser should reject:

• Unsupported operations ("What is 52 cubed?")
• Non-math questions ("Who is the President of the United States")
• Word problems with invalid syntax ("What is 1 plus plus 2?")

## Bonus — Exponentials

If you'd like, handle exponentials.

What is 2 raised to the 5th power?

32

## Setup

Go through the setup instructions for Java to install the necessary dependencies:

https://exercism.io/tracks/java/installation

# Running the tests

You can run all the tests for an exercise by entering the following in your terminal:

``````\$ gradle test
``````

Use `gradlew.bat` if you're on Windows

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by removing the `@Ignore("Remove to run test")` annotation.

## Source

Inspired by one of the generated questions in the Extreme Startup game. https://github.com/rchatley/extreme_startup

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### WordProblemSolverTest.java

``````import org.junit.Ignore;
import org.junit.Rule;
import org.junit.Test;
import org.junit.Before;
import org.junit.rules.ExpectedException;

import static org.junit.Assert.assertEquals;

public class WordProblemSolverTest {

@Rule
public ExpectedException expectedException = ExpectedException.none();

WordProblemSolver solver;

@Before
public void setup() {
solver = new WordProblemSolver();
}

@Test
public void testJustANumber() {
assertEquals(5, solver.solve("What is 5?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(2, solver.solve("What is 1 plus 1?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(55, solver.solve("What is 53 plus 2?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(-11, solver.solve("What is -1 plus -10?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(45801, solver.solve("What is 123 plus 45678?"));
}

@Ignore("Remove to run test")
@Test
public void testSingleSubtraction() {
assertEquals(16, solver.solve("What is 4 minus -12?"));
}

@Ignore("Remove to run test")
@Test
public void testSingleMultiplication() {
assertEquals(-75, solver.solve("What is -3 multiplied by 25?"));
}

@Ignore("Remove to run test")
@Test
public void testSingleDivision() {
assertEquals(-11, solver.solve("What is 33 divided by -3?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(3, solver.solve("What is 1 plus 1 plus 1?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(8, solver.solve("What is 1 plus 5 minus -2?"));
}

@Ignore("Remove to run test")
@Test
public void testMultipleSubtractions() {
assertEquals(3, solver.solve("What is 20 minus 4 minus 13?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(14, solver.solve("What is 17 minus 6 plus 3?"));
}

@Ignore("Remove to run test")
@Test
public void testMultipleMultiplications() {
assertEquals(-12, solver.solve("What is 2 multiplied by -2 multiplied by 3?"));
}

@Ignore("Remove to run test")
@Test
assertEquals(-8, solver.solve("What is -3 plus 7 multiplied by -2?"));
}

@Ignore("Remove to run test")
@Test
public void testMultipleDivisions() {
assertEquals(2, solver.solve("What is -12 divided by 2 divided by -3?"));
}

@Ignore("Remove to run test")
@Test
public void testUnknownOperation() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

solver.solve("What is 52 cubed?");
}

@Ignore("Remove to run test")
@Test
public void testNonMathQuestion() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

// See https://en.wikipedia.org/wiki/President_of_the_United_States if you really need to know!
solver.solve("Who is the President of the United States?");
}

@Ignore("Remove to run test")
@Test
public void testMissingAnOperand() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

solver.solve("What is 1 plus?");
}

@Ignore("Remove to run test")
@Test
public void testNoOperandsOrOperators() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

solver.solve("What is?");
}

@Ignore("Remove to run test")
@Test
public void testTwoOperationsInARow() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

solver.solve("What is 1 plus plus 2?");
}

@Ignore("Remove to run test")
@Test
public void testTwoNumbersAfterOperation() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

solver.solve("What is 1 plus 2 1?");
}

@Ignore("Remove to run test")
@Test
public void testPostfixNotation() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

solver.solve("What is 1 2 plus?");
}

@Ignore("Remove to run test")
@Test
public void testPrefixNotation() {
expectedException.expect(IllegalArgumentException.class);
expectedException.expectMessage("I'm sorry, I don't understand the question!");

solver.solve("What is plus 1 2?");
}
}``````
``````import java.util.ArrayList;
import java.util.Arrays;
import java.util.Queue;

public class WordProblemSolver {

public WordProblemSolver() {}

public ArrayList<Object> getProblem(String s) {
s = s.replaceAll("by ", "");
String[] sa = s.split(" ");
s = s.replaceAll("by ", ""); //Delete by
//s = s.replaceAll("?", ""); //Delete ?
System.out.println(Arrays.toString(sa)); //debug
//Queue<Object> operations = new Queue<Object>(); this is acting up
ArrayList<Object> elements = new ArrayList<Object>();

for(int i = 2; i < sa.length; i++) { //first 2 are "What is", last is question mark

if(i == sa.length -1) { //delete question mark
sa[i] = sa[i].replace("?", "");
}

if(isNumber(sa[i])) {

if(elements.size() >= 1 && !isOperation(sa[i-1])){ //weird notation thing
throw new IllegalArgumentException("I'm sorry, I don't understand the question!");
}

}
else if(isOperation(sa[i])) {
if(!isNumber(sa[i-1])) {
throw new IllegalArgumentException("I'm sorry, I don't understand the question!");
}
}
else { //not valid so throw!
throw new IllegalArgumentException("I'm sorry, I don't understand the question!");
}
}
if(elements.size() == 0) { //no real question
throw new IllegalArgumentException("I'm sorry, I don't understand the question!");
}
else if(elements.size() % 2 == 0) { //obviously missing an element
throw new IllegalArgumentException("I'm sorry, I don't understand the question!");
}

return elements;
}

public int solve(String s) {
ArrayList<Object> values = this.getProblem(s); //well formed at this point

int result = (int) values.get(0);

for(int i = 1; i < values.size(); i++) {
i++;
int n = (int) values.get(i);
result += n;
}
else if(values.get(i) == Operations.SUBTRACT) {
i++; //to access next number
int n = (int) values.get(i);
result -= n;
}
else if(values.get(i) == Operations.MULTIPLY) {
i++; //to access next number
int n = (int) values.get(i);
result *= n;
}
else if(values.get(i) == Operations.DIVIDE) {
i++; //to access next number
int n = (int) values.get(i);
result /= n;
}
}
return result;
}

public static boolean isNumber(String s) {
try
{
Integer.parseInt(s);
} catch(NumberFormatException e) {
return false; //is not a number
}
return true; //was
}

public static boolean isOperation(String s) {
return s.equals("plus") || s.equals("minus") || s.equals("multiplied") || s.equals("divided");
}

public static Operations giveOperation(String s){
if(s.equals("plus")) {
}
else if(s.equals("minus")) {
return Operations.SUBTRACT;
}
else if(s.equals("multiplied")) {
return Operations.MULTIPLY;
}
else { //thats okay because we first check if we get a division
return Operations.DIVIDE;
}
}

/*public static void main(String args[]) {
System.out.println(WordProblemSolver.isNumber("A"));
System.out.println(WordProblemSolver.isNumber("28"));
WordProblemSolver a = new WordProblemSolver();
System.out.println(a.solve("What is 1 2 plus?"));
}*/
}

enum Operations{

SUBTRACT,
MULTIPLY,
DIVIDE

}``````