From 2f61515fb71912fbed5f2a4472de8d8e6b80ab2b Mon Sep 17 00:00:00 2001
From: jacekpoz <jacekpoz@cock.li>
Date: Fri, 12 Apr 2024 10:21:55 +0200
Subject: [PATCH] java lab2 improvements

---
 .../app/src/main/java/pl/jacekpoz/GF.java     | 53 ++++++++++++++-----
 .../app/src/main/java/pl/jacekpoz/Main.java   |  9 ++++
 2 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/lab2/zad2/app/src/main/java/pl/jacekpoz/GF.java b/lab2/zad2/app/src/main/java/pl/jacekpoz/GF.java
index d47e998..a21c18b 100644
--- a/lab2/zad2/app/src/main/java/pl/jacekpoz/GF.java
+++ b/lab2/zad2/app/src/main/java/pl/jacekpoz/GF.java
@@ -15,19 +15,19 @@ public class GF {
         this.value = value;
     }
 
-    public GF addition(final GF rhs) throws IllegalArgumentException {
+    public GF add(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
 
         return new GF((this.value + rhs.value) % this.characteristic, this.characteristic);
     }
 
-    public void additionAssignment(final GF rhs) throws IllegalArgumentException {
+    public void addAssign(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
 
-        this.value = this.addition(rhs).value;
+        this.value = this.add(rhs).value;
     }
 
-    public GF subtraction(final GF rhs) throws IllegalArgumentException {
+    public GF subtract(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
         if (this.value < rhs.value) {
             return new GF(this.characteristic - (rhs.value - this.value), this.characteristic);
@@ -35,40 +35,55 @@ public class GF {
         return new GF((this.value - rhs.value), this.characteristic);
     }
 
-    public void subtractionAssignment(final GF rhs) throws IllegalArgumentException {
+    public void subtractAssign(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
 
-        this.value = this.subtraction(rhs).value;
+        this.value = this.subtract(rhs).value;
     }
 
-    public GF multiplication(final GF rhs) throws IllegalArgumentException {
+    public GF multiply(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
 
         return new GF((this.value * rhs.value) % this.characteristic, this.characteristic);
     }
 
-    public void multiplicationAssignment(final GF rhs) throws IllegalArgumentException {
+    public void multiplyAssign(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
 
-        this.value = this.multiplication(rhs).value;
+        this.value = this.multiply(rhs).value;
     }
 
-    public GF division(final GF rhs) throws IllegalArgumentException {
+    public GF divide(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
+        if (rhs.value == 0) {
+            throw new IllegalArgumentException("division by 0 is illegal");
+        }
 
-        return new GF((this.value / rhs.value) % this.characteristic, this.characteristic);
+        int inverse = 1;
+        for (int i = 1; i < this.characteristic; i++) {
+            if ((rhs.value * i) % this.characteristic == 1) {
+                inverse = i;
+                break;
+            }
+        }
+    
+        return new GF((this.value * inverse) % this.characteristic, this.characteristic);
     }
 
-    public void divisionAssignment(final GF rhs) throws IllegalArgumentException {
+    public void divideAssign(final GF rhs) throws IllegalArgumentException {
         verifyCharacteristics(this, rhs);
 
-        this.value = this.division(rhs).value;
+        this.value = this.divide(rhs).value;
     }
 
     public int getCharacteristic() {
         return this.characteristic;
     }
 
+    public int getValue() {
+        return this.value;
+    }
+
     @Override
     public boolean equals(Object obj) {
         if (obj instanceof GF rhs) {
@@ -82,6 +97,18 @@ public class GF {
         return false;
     }
 
+    public int compare(GF rhs) throws IllegalArgumentException {
+        verifyCharacteristics(this, rhs);
+
+        if (this.value < rhs.value) {
+            return -1;
+        } else if (this.value > rhs.value) {
+            return 1;
+        } else {
+            return 0;
+        }
+    }
+
     @Override
     public String toString() {
         return "GF<" + this.characteristic + ">(" + this.value + ")";
diff --git a/lab2/zad2/app/src/main/java/pl/jacekpoz/Main.java b/lab2/zad2/app/src/main/java/pl/jacekpoz/Main.java
index 6681e1a..6a90155 100644
--- a/lab2/zad2/app/src/main/java/pl/jacekpoz/Main.java
+++ b/lab2/zad2/app/src/main/java/pl/jacekpoz/Main.java
@@ -1,6 +1,15 @@
 package pl.jacekpoz;
+import java.util.Scanner;
 
 public class Main {
     public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        GF a = new GF(1234577, scanner.nextInt());
+        GF b = new GF(1234577, scanner.nextInt());
+
+        System.out.println(a + " + " + b + " = " + (a.add(b)));
+        System.out.println(a + " - " + b + " = " + (a.subtract(b)));
+        System.out.println(a + " * " + b + " = " + (a.multiply(b)));
+        System.out.println(a + " / " + b + " = " + (a.divide(b)));
     }
 }