diff --git a/checkstyle.xml b/checkstyle.xml index 7a91d521..03bcdb1d 100644 --- a/checkstyle.xml +++ b/checkstyle.xml @@ -115,7 +115,7 @@ - + diff --git a/src/main/java/com/thealgorithms/ciphers/DES.java b/src/main/java/com/thealgorithms/ciphers/DES.java index 8e44f091..d0a24f1e 100644 --- a/src/main/java/com/thealgorithms/ciphers/DES.java +++ b/src/main/java/com/thealgorithms/ciphers/DES.java @@ -8,7 +8,7 @@ package com.thealgorithms.ciphers; public class DES { private String key; - private String[] subKeys; + private final String[] subKeys; private void sanitize(String key) { int length = key.length(); @@ -32,48 +32,48 @@ public class DES { 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[] KEY_SHIFTS = {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 - 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}; + // Permutation table, used in the Feistel function post s-box usage + static final 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 - static int[] IPinverse = {40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25}; + static final int[] IP_INVERSE = {40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25}; private String[] getSubkeys(String originalKey) { - StringBuilder permutedKey = new StringBuilder(); // Initial permutation of keys via PC1 + 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)); @@ -91,7 +91,7 @@ public class DES { D0 = Dn; } - // Let us shrink the keys to 48 bits (well, characters here) using PC2 + // Let us shrink the keys to 48 bits (well, characters here) using pc2 for (i = 0; i < 16; i++) { String key = subKeys[i]; permutedKey.setLength(0); @@ -137,7 +137,7 @@ public class DES { 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(); @@ -147,13 +147,13 @@ public class DES { 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); } StringBuilder permutedString = new StringBuilder(); for (i = 0; i < 32; i++) { - permutedString.append(substitutedString.charAt(permutation[i] - 1)); + permutedString.append(substitutedString.charAt(PERMUTATION[i] - 1)); } return permutedString.toString(); @@ -178,7 +178,7 @@ public class DES { String combinedBlock = R0 + L0; // Reverse the 16th block permutedMessage.setLength(0); for (i = 0; i < 64; i++) { - permutedMessage.append(combinedBlock.charAt(IPinverse[i] - 1)); + permutedMessage.append(combinedBlock.charAt(IP_INVERSE[i] - 1)); } return permutedMessage.toString(); } diff --git a/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java b/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java index 9e1516ec..b57dec97 100644 --- a/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java +++ b/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java @@ -10,13 +10,13 @@ public final class 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 final class FordFulkerson { } private static int networkFlow(int source, int sink) { - flow = new int[V][V]; + flow = new int[vertexCount][vertexCount]; int totalFlow = 0; while (true) { - Vector parent = new Vector<>(V); - for (int i = 0; i < V; i++) { + Vector parent = new Vector<>(vertexCount); + for (int i = 0; i < vertexCount; i++) { parent.add(-1); } Queue q = new LinkedList<>(); @@ -45,7 +45,7 @@ public final class FordFulkerson { 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/RabinKarp.java b/src/main/java/com/thealgorithms/others/RabinKarp.java index 8188a1a7..f8ca33be 100644 --- a/src/main/java/com/thealgorithms/others/RabinKarp.java +++ b/src/main/java/com/thealgorithms/others/RabinKarp.java @@ -11,15 +11,15 @@ public final class RabinKarp { private RabinKarp() { } - public static Scanner SCANNER = null; + public static Scanner scanner = null; public static final int ALPHABET_SIZE = 256; public static void main(String[] args) { - SCANNER = new Scanner(System.in); + scanner = new Scanner(System.in); System.out.println("Enter String"); - String text = SCANNER.nextLine(); + String text = scanner.nextLine(); System.out.println("Enter pattern"); - String pattern = SCANNER.nextLine(); + String pattern = scanner.nextLine(); int q = 101; searchPat(text, pattern, q); diff --git a/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java b/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java index 15148de1..22979e59 100644 --- a/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java +++ b/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java @@ -5,13 +5,13 @@ package com.thealgorithms.others; */ 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() { } public static final int CHARS = 256; - public static int[][] FA; + public static int[][] fa; public static Scanner scanner = null; public static void main(String[] args) { @@ -30,13 +30,13 @@ public final class StringMatchFiniteAutomata { int m = pat.length(); int n = text.length(); - FA = new int[m + 1][CHARS]; + fa = new int[m + 1][CHARS]; - computeFA(pat, m, FA); + computeFA(pat, m, fa); int state = 0; for (int i = 0; i < n; i++) { - state = FA[state][text.charAt(i)]; + state = fa[state][text.charAt(i)]; if (state == m) { System.out.println("Pattern found at index " + (i - m + 1)); @@ -44,11 +44,11 @@ public final class StringMatchFiniteAutomata { } } - // Computes finite automata for the partern - public static void computeFA(String pat, int m, int[][] FA) { + // 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) { - FA[state][x] = getNextState(pat, m, state, x); + fa[state][x] = getNextState(pat, m, state, x); } } }