# Solving the Pythagorean Triple in Java

## The challenge

Given an array of 3 integers a, b and c, determine if they form a pythagorean triple.

A pythagorean triple is formed when:

## c2 = a2 + b2

where c is the largest value of a, b, c.

For example: a = 3, b = 4, c = 5 forms a pythagorean triple, because 52 = 32 + 42

### Return Values

• 1 if ab and c form a pythagorean triple
• 0 if ab and c do not form a pythagorean triple
• For Python: return True or False

## The solution in Java code

Option 1:

public class PythagoreanTriple {
public int pythagoreanTriple(int[] triple){
return triple[0] * triple[0] + triple[1] * triple[1] == triple[2] * triple[2] ? 1 : 0;
}
}

Option 2:

class PythagoreanTriple {
int pythagoreanTriple(final int[] triple) {
final int a2 = triple[0]*triple[0];
final int b2 = triple[1]*triple[1];
final int c2 = triple[2]*triple[2];
return a2 + b2 == c2 || a2 + c2 == b2 || b2 + c2 == a2 ? 1 : 0;
}
}

Option 3:

import java.util.Arrays;
import java.util.Collections;
import java.util.stream.Stream;

public class PythagoreanTriple {

public int pythagoreanTriple(int[] triple){
Integer[] toIntArray = Arrays.stream(triple).boxed().toArray(Integer[]::new);
Arrays.sort(toIntArray, Collections.reverseOrder());
return Math.pow(toIntArray[0], 2)==(Math.pow(toIntArray[1], 2)+Math.pow(toIntArray[2], 2)) ? 1 : 0;

}

}

## Test cases to validate our solution

import org.junit.Test;
import static org.junit.Assert.assertEquals;
import org.junit.runners.JUnit4;

public class PythagoreanTripleTest{
static int[] p1={3,4,5};
static int[] p2={3,5,7};

PythagoreanTriple pT = new PythagoreanTriple();

@Test
public void validTriple() {
assertEquals(1, pT.pythagoreanTriple(p1));
}

@Test
public void invalidTriple(){
assertEquals(0,pT.pythagoreanTriple(p2));
}
}

## More comprehensive test cases

import org.junit.Test;
import static org.junit.Assert.assertEquals;
import org.junit.runners.JUnit4;

public class PythagoreanTripleTest{

PythagoreanTriple pT = new PythagoreanTriple();

// valid cases
static int[] p1 = { 3, 4, 5 };
static int[] p2 = { 5, 12, 13 };
static int[] p3 = { 6, 8, 10 };
static int[] p4 = { 7, 24, 25 };
static int[] p5 = { 8, 15, 17 };
static int[] p6 = { 9, 12, 15 };
static int[] p7 = { 9, 40, 41 };
static int[] p8 = { 10, 24, 26 };
static int[] p9 = { 12, 16, 20 };
static int[] p10 = { 12, 16, 20 };
static int[] p11 = { 14,48,50 };
static int[] p12 = { 15,20,25 };
static int[] p13 = { 15,36,39 };
static int[] p14 = { 16, 30, 34 };
static int[] p15 = { 18, 24, 30 };
static int[] p16 = { 20, 21, 29 };
static int[] p17 = { 21, 28, 35 };
static int[] p18 = { 24, 32, 40 };
static int[] p19 = { 27, 36, 45 };
static int[] p20 = { 30, 40, 50 };

// invalid cases
static int[] p21 = {70,18,8};
static int[] p22 = {50,19,19};
static int[] p23 = {44,17,15};
static int[] p24 = {4,54,5};
static int[] p25 = {33,11,24};
static int[] p26 = {69,11,15};
static int[] p27 = {77,12,27};
static int[] p28 = {35,39,13};
static int[] p29 = {90,44,18};
static int[] p30 = {31,8,22};
static int[] p31 = {22,30,7};
static int[] p32 = {94,16,25};
static int[] p33 = {84,37,18};
static int[] p34 = {84,19,23};
static int[] p35 = {9,45,21};
static int[] p36 = {61,18,9};
static int[] p37 = {93,50,25};
static int[] p38 = {10,21,17};
static int[] p39 = {65,26,3};
static int[] p40 = {39,31,6};

@Test
public void validTriple() {
assertEquals(1, pT.pythagoreanTriple(p1));
assertEquals(1, pT.pythagoreanTriple(p2));
assertEquals(1, pT.pythagoreanTriple(p3));
assertEquals(1, pT.pythagoreanTriple(p4));
assertEquals(1, pT.pythagoreanTriple(p5));
assertEquals(1, pT.pythagoreanTriple(p6));
assertEquals(1, pT.pythagoreanTriple(p7));
assertEquals(1, pT.pythagoreanTriple(p8));
assertEquals(1, pT.pythagoreanTriple(p9));
assertEquals(1, pT.pythagoreanTriple(p10));
assertEquals(1, pT.pythagoreanTriple(p11));
assertEquals(1, pT.pythagoreanTriple(p12));
assertEquals(1, pT.pythagoreanTriple(p13));
assertEquals(1, pT.pythagoreanTriple(p14));
assertEquals(1, pT.pythagoreanTriple(p15));
assertEquals(1, pT.pythagoreanTriple(p16));
assertEquals(1, pT.pythagoreanTriple(p17));
assertEquals(1, pT.pythagoreanTriple(p18));
assertEquals(1, pT.pythagoreanTriple(p19));
assertEquals(1, pT.pythagoreanTriple(p20));
}

@Test
public void invalidTriple(){
assertEquals(0, pT.pythagoreanTriple(p21));
assertEquals(0, pT.pythagoreanTriple(p22));
assertEquals(0, pT.pythagoreanTriple(p23));
assertEquals(0, pT.pythagoreanTriple(p24));
assertEquals(0, pT.pythagoreanTriple(p25));
assertEquals(0, pT.pythagoreanTriple(p26));
assertEquals(0, pT.pythagoreanTriple(p27));
assertEquals(0, pT.pythagoreanTriple(p28));
assertEquals(0, pT.pythagoreanTriple(p29));
assertEquals(0, pT.pythagoreanTriple(p30));
assertEquals(0, pT.pythagoreanTriple(p31));
assertEquals(0, pT.pythagoreanTriple(p32));
assertEquals(0, pT.pythagoreanTriple(p33));
assertEquals(0, pT.pythagoreanTriple(p34));
assertEquals(0, pT.pythagoreanTriple(p35));
assertEquals(0, pT.pythagoreanTriple(p36));
assertEquals(0, pT.pythagoreanTriple(p37));
assertEquals(0, pT.pythagoreanTriple(p38));
assertEquals(0, pT.pythagoreanTriple(p39));
assertEquals(0, pT.pythagoreanTriple(p40));
}
}
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