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Add binary addition (#5593)

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This commit is contained in:
Muhammad Junaid Khalid
2024-10-07 19:17:04 +05:00
committed by GitHub
parent a2457bd1ff
commit cacd23a2bd
3 changed files with 173 additions and 0 deletions
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2
DIRECTORY.md
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@ -272,6 +272,7 @@
* [GrahamScan](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/geometry/GrahamScan.java)
* greedyalgorithms
* [ActivitySelection](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/greedyalgorithms/ActivitySelection.java)
* [BinaryAddition](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/greedyalgorithms/BinaryAddition.java)
* [CoinChange](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/greedyalgorithms/CoinChange.java)
* [DigitSeparation](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/greedyalgorithms/DigitSeparation.java)
* [FractionalKnapsack](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/greedyalgorithms/FractionalKnapsack.java)
@ -787,6 +788,7 @@
* [GrahamScanTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/geometry/GrahamScanTest.java)
* greedyalgorithms
* [ActivitySelectionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/greedyalgorithms/ActivitySelectionTest.java)
* [BinaryAdditionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/greedyalgorithms/BinaryAdditionTest.java)
* [CoinChangeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/greedyalgorithms/CoinChangeTest.java)
* [DigitSeparationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/greedyalgorithms/DigitSeparationTest.java)
* [FractionalKnapsackTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/greedyalgorithms/FractionalKnapsackTest.java)

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src/main/java/com/thealgorithms/greedyalgorithms/BinaryAddition.java Normal file
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package com.thealgorithms.greedyalgorithms;
import java.util.Collections;
/**
* BinaryAddition class to perform binary addition of two binary strings.
*/
public class BinaryAddition {
/**
* Computes the sum of two binary characters and a carry.
* @param a First binary character ('0' or '1').
* @param b Second binary character ('0' or '1').
* @param carry The carry from the previous operation ('0' or '1').
* @return The sum as a binary character ('0' or '1').
*/
public char sum(char a, char b, char carry) {
int count = 0;
if (a == '1') {
count++;
}
if (b == '1') {
count++;
}
if (carry == '1') {
count++;
}
return count % 2 == 0 ? '0' : '1';
}
/**
* Computes the carry for the next higher bit from two binary characters and a carry.
* @param a First binary character ('0' or '1').
* @param b Second binary character ('0' or '1').
* @param carry The carry from the previous operation ('0' or '1').
* @return The carry for the next bit ('0' or '1').
*/
public char carry(char a, char b, char carry) {
int count = 0;
if (a == '1') {
count++;
}
if (b == '1') {
count++;
}
if (carry == '1') {
count++;
}
return count >= 2 ? '1' : '0';
}
/**
* Adds two binary strings and returns their sum as a binary string.
* @param a First binary string.
* @param b Second binary string.
* @return Binary string representing the sum of the two binary inputs.
*/
public String addBinary(String a, String b) {
// Padding the shorter string with leading zeros
int maxLength = Math.max(a.length(), b.length());
a = String.join("", Collections.nCopies(maxLength - a.length(), "0")) + a;
b = String.join("", Collections.nCopies(maxLength - b.length(), "0")) + b;
StringBuilder result = new StringBuilder();
char carry = '0';
// Iterating over the binary strings from the least significant to the most significant bit
for (int i = maxLength - 1; i >= 0; i--) {
char sum = sum(a.charAt(i), b.charAt(i), carry);
carry = carry(a.charAt(i), b.charAt(i), carry);
result.append(sum);
}
// If there's a remaining carry, append it
if (carry == '1') {
result.append('1');
}
// Reverse the result as we constructed it from the least significant bit
return result.reverse().toString();
}
}

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src/test/java/com/thealgorithms/greedyalgorithms/BinaryAdditionTest.java Normal file
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package com.thealgorithms.greedyalgorithms;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
public class BinaryAdditionTest {
BinaryAddition binaryAddition = new BinaryAddition();
@Test
public void testEqualLengthNoCarry() {
String a = "1010";
String b = "1101";
String expected = "10111";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testEqualLengthWithCarry() {
String a = "1111";
String b = "1111";
String expected = "11110";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testDifferentLengths() {
String a = "101";
String b = "11";
String expected = "1000";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testAllZeros() {
String a = "0";
String b = "0";
String expected = "0";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testAllOnes() {
String a = "1111";
String b = "1111";
String expected = "11110";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testOneZeroString() {
String a = "0";
String b = "10101";
String expected = "10101";
assertEquals(expected, binaryAddition.addBinary(a, b));
// Test the other way around
a = "10101";
b = "0";
expected = "10101";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testLargeBinaryNumbers() {
String a = "101010101010101010101010101010";
String b = "110110110110110110110110110110";
String expected = "1100001100001100001100001100000";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testOneMuchLonger() {
String a = "1";
String b = "11111111";
String expected = "100000000";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testEmptyStrings() {
String a = "";
String b = "";
String expected = ""; // Adding two empty strings should return 0
assertEquals(expected, binaryAddition.addBinary(a, b));
}
@Test
public void testAlternatingBits() {
String a = "10101010";
String b = "01010101";
String expected = "11111111";
assertEquals(expected, binaryAddition.addBinary(a, b));
}
}