Refractored classes: Marked static variables as private static final and performed suitable renaming and corrected spelling mistakes in comments

vaibhavw-techp · vaibhavw-techp · commit 34734d738363 · 2024-05-25T12:27:51.000+05:30
diff --git a/src/main/java/com/thealgorithms/ciphers/DES.java b/src/main/java/com/thealgorithms/ciphers/DES.java
@@ -8,7 +8,7 @@
 public class DES {
 
     private String key;
-    private String[] subKeys;
+    private final String[] subKeys;
 
     private void sanitize(String key) {
         int length = key.length();
@@ -32,41 +32,41 @@ public void setKey(String key) {
         this.key = key;
     }
 
-    // Permutation table to convert initial 64 bit key to 56 bit key
-    private static int[] pc1 = {57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36, 63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4};
+    // Permutation table to convert initial 64-bit key to 56 bit key
+    private static final int[] PC1 = {57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36, 63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4};
 
     // Lookup table used to shift the initial key, in order to generate the subkeys
-    private static int[] keyShifts = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};
+    private static final int[] KEY_SHIFTS = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};
 
     // Table to convert the 56 bit subkeys to 48 bit subkeys
-    private static int[] pc2 = {14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32};
+    private static final int[] PC2 = {14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32};
 
-    // Initial permutatation of each 64 but message block
-    private static int[] ip = {58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19, 11, 3, 61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7};
+    // Initial permutation of each 64 but message block
+    private static final int[] IP = {58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19, 11, 3, 61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7};
 
     // Expansion table to convert right half of message blocks from 32 bits to 48 bits
-    private static int[] expansion = {32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17, 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32, 1};
+    private static final int[] EXPANSION = {32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17, 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32, 1};
 
     // The eight substitution boxes are defined below
-    private static int[][] s1 = {{14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7}, {0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8}, {4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0}, {15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13}};
+    private static final int[][] S1 = {{14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7}, {0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8}, {4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0}, {15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13}};
 
-    private static int[][] s2 = {{15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10}, {3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5}, {0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15}, {13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9}};
+    private static final int[][] S2 = {{15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10}, {3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5}, {0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15}, {13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9}};
 
-    private static int[][] s3 = {{10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8}, {13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1}, {13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7}, {1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12}};
+    private static final int[][] S3 = {{10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8}, {13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1}, {13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7}, {1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12}};
 
-    private static int[][] s4 = {{7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15}, {13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9}, {10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4}, {3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14}};
+    private static final int[][] S4 = {{7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15}, {13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9}, {10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4}, {3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14}};
 
-    private static int[][] s5 = {{2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9}, {14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6}, {4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14}, {11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3}};
+    private static final int[][] S5 = {{2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9}, {14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6}, {4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14}, {11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3}};
 
-    private static int[][] s6 = {{12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11}, {10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8}, {9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6}, {4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13}};
+    private static final int[][] S6 = {{12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11}, {10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8}, {9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6}, {4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13}};
 
-    private static int[][] s7 = {{4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1}, {13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6}, {1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2}, {6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12}};
+    private static final int[][] S7 = {{4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1}, {13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6}, {1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2}, {6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12}};
 
-    private static int[][] s8 = {{13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7}, {1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2}, {7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8}, {2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11}};
+    private static final int[][] S8 = {{13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7}, {1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2}, {7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8}, {2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11}};
 
-    private static int[][][] s = {s1, s2, s3, s4, s5, s6, s7, s8};
+    private static final int[][][] S = {S1, S2, S3, S4, S5, S6, S7, S8};
 
-    // Permutation table, used in the feistel function post s-box usage
+    // Permutation table, used in the Feistel function post s-box usage
     static int[] permutation = {16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25};
 
     // Table used for final inversion of the message box after 16 rounds of Feistel Function
@@ -76,16 +76,16 @@ private String[] getSubkeys(String originalKey) {
         StringBuilder permutedKey = new StringBuilder(); // Initial permutation of keys via pc1
         int i, j;
         for (i = 0; i < 56; i++) {
-            permutedKey.append(originalKey.charAt(pc1[i] - 1));
+            permutedKey.append(originalKey.charAt(PC1[i] - 1));
         }
         String[] subKeys = new String[16];
         String initialPermutedKey = permutedKey.toString();
         String C0 = initialPermutedKey.substring(0, 28), D0 = initialPermutedKey.substring(28);
 
         // We will now operate on the left and right halves of the permutedKey
         for (i = 0; i < 16; i++) {
-            String Cn = C0.substring(keyShifts[i]) + C0.substring(0, keyShifts[i]);
-            String Dn = D0.substring(keyShifts[i]) + D0.substring(0, keyShifts[i]);
+            String Cn = C0.substring(KEY_SHIFTS[i]) + C0.substring(0, KEY_SHIFTS[i]);
+            String Dn = D0.substring(KEY_SHIFTS[i]) + D0.substring(0, KEY_SHIFTS[i]);
             subKeys[i] = Cn + Dn;
             C0 = Cn; // Re-assign the values to create running permutation
             D0 = Dn;
@@ -96,7 +96,7 @@ private String[] getSubkeys(String originalKey) {
             String key = subKeys[i];
             permutedKey.setLength(0);
             for (j = 0; j < 48; j++) {
-                permutedKey.append(key.charAt(pc2[j] - 1));
+                permutedKey.append(key.charAt(PC2[j] - 1));
             }
             subKeys[i] = permutedKey.toString();
         }
@@ -137,7 +137,7 @@ private String feistel(String messageBlock, String key) {
         int i;
         StringBuilder expandedKey = new StringBuilder();
         for (i = 0; i < 48; i++) {
-            expandedKey.append(messageBlock.charAt(expansion[i] - 1));
+            expandedKey.append(messageBlock.charAt(EXPANSION[i] - 1));
         }
         String mixedKey = XOR(expandedKey.toString(), key);
         StringBuilder substitutedString = new StringBuilder();
@@ -147,7 +147,7 @@ private String feistel(String messageBlock, String key) {
             String block = mixedKey.substring(i, i + 6);
             int row = (block.charAt(0) - 48) * 2 + (block.charAt(5) - 48);
             int col = (block.charAt(1) - 48) * 8 + (block.charAt(2) - 48) * 4 + (block.charAt(3) - 48) * 2 + (block.charAt(4) - 48);
-            String substitutedBlock = pad(Integer.toBinaryString(s[i / 6][row][col]), 4);
+            String substitutedBlock = pad(Integer.toBinaryString(S[i / 6][row][col]), 4);
             substitutedString.append(substitutedBlock);
         }
 
@@ -163,7 +163,7 @@ private String encryptBlock(String message, String[] keys) {
         StringBuilder permutedMessage = new StringBuilder();
         int i;
         for (i = 0; i < 64; i++) {
-            permutedMessage.append(message.charAt(ip[i] - 1));
+            permutedMessage.append(message.charAt(IP[i] - 1));
         }
         String L0 = permutedMessage.substring(0, 32), R0 = permutedMessage.substring(32);
 
diff --git a/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java b/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java
@@ -10,13 +10,13 @@ private FordFulkerson() {
 
     static final int INF = 987654321;
     // edges
-    static int v;
+    static int vertexCount;
     static int[][] capacity, flow;
 
     public static void main(String[] args) {
-        System.out.println("V : 6");
-        v = 6;
-        capacity = new int[v][v];
+        System.out.println("Vertex Count : 6");
+        vertexCount = 6;
+        capacity = new int[vertexCount][vertexCount];
 
         capacity[0][1] = 12;
         capacity[0][3] = 13;
@@ -32,11 +32,11 @@ public static void main(String[] args) {
     }
 
     private static int networkFlow(int source, int sink) {
-        flow = new int[v][v];
+        flow = new int[vertexCount][vertexCount];
         int totalFlow = 0;
         while (true) {
-            Vector<Integer> parent = new Vector<>(v);
-            for (int i = 0; i < v; i++) {
+            Vector<Integer> parent = new Vector<>(vertexCount);
+            for (int i = 0; i < vertexCount; i++) {
                 parent.add(-1);
             }
             Queue<Integer> q = new LinkedList<>();
@@ -45,7 +45,7 @@ private static int networkFlow(int source, int sink) {
             while (!q.isEmpty() && parent.get(sink) == -1) {
                 int here = q.peek();
                 q.poll();
-                for (int there = 0; there < v; ++there) {
+                for (int there = 0; there < vertexCount; ++there) {
                     if (capacity[here][there] - flow[here][there] > 0 && parent.get(there) == -1) {
                         q.add(there);
                         parent.set(there, here);
diff --git a/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java b/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java
@@ -5,7 +5,7 @@
  */
 import java.util.Scanner;
 
-// An implementaion of string matching using finite automata
+// An implementation of string matching using finite automata
 public final class StringMatchFiniteAutomata {
     private StringMatchFiniteAutomata() {
     }
@@ -44,7 +44,7 @@ public static void searchPat(String text, String pat) {
         }
     }
 
-    // Computes finite automata for the partern
+    // Computes finite automata for the pattern
     public static void computeFA(String pat, int m, int[][] fa) {
         for (int state = 0; state <= m; ++state) {
             for (int x = 0; x < CHARS; ++x) {

Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,7 @@`
`5`	`5`	`*/`
`6`	`6`	`import java.util.Scanner;`
`7`	`7`
`8`		`-// An implementaion of string matching using finite automata`
	`8`	`+// An implementation of string matching using finite automata`
`9`	`9`	`public final class StringMatchFiniteAutomata {`
`10`	`10`	`private StringMatchFiniteAutomata() {`
`11`	`11`	`}`
`@@ -44,7 +44,7 @@ public static void searchPat(String text, String pat) {`
`44`	`44`	`}`
`45`	`45`	`}`
`46`	`46`
`47`		`- // Computes finite automata for the partern`
	`47`	`+ // Computes finite automata for the pattern`
`48`	`48`	`public static void computeFA(String pat, int m, int[][] fa) {`
`49`	`49`	`for (int state = 0; state <= m; ++state) {`
`50`	`50`	`for (int x = 0; x < CHARS; ++x) {`