style: enable LocalVariableName in CheckStyle

checkstyle.xml

@@ -110,7 +110,7 @@
     <!-- See https://checkstyle.org/checks/naming/index.html -->
     <module name="ConstantName"/>
     <module name="LocalFinalVariableName"/>
-    <!-- TODO <module name="LocalVariableName"/> -->
+    <module name="LocalVariableName"/>
     <!-- TODO <module name="MemberName"/> -->
     <module name="MethodName"/>
     <module name="PackageName"/>

src/main/java/com/thealgorithms/ciphers/AffineCipher.java

@@ -27,7 +27,7 @@ static String encryptMessage(char[] msg) {
 
     static String decryptCipher(String cipher) {
         String msg = "";
-        int a_inv = 0;
+        int aInv = 0;
         int flag = 0;
 
         // Find a^-1 (the multiplicative inverse of a
@@ -38,15 +38,15 @@ static String decryptCipher(String cipher) {
             // Check if (a*i)%26 == 1,
             // then i will be the multiplicative inverse of a
             if (flag == 1) {
-                a_inv = i;
+                aInv = i;
             }
         }
         for (int i = 0; i < cipher.length(); i++) {
             /*Applying decryption formula a^-1 ( x - b ) mod m
             {here x is cipher[i] and m is 26} and added 'A'
             to bring it in range of ASCII alphabet[ 65-90 | A-Z ] */
             if (cipher.charAt(i) != ' ') {
-                msg = msg + (char) (((a_inv * ((cipher.charAt(i) + 'A' - b)) % 26)) + 'A');
+                msg = msg + (char) (((aInv * ((cipher.charAt(i) + 'A' - b)) % 26)) + 'A');
             } else { // else simply append space character
                 msg += cipher.charAt(i);
             }

src/main/java/com/thealgorithms/ciphers/DES.java

@@ -81,16 +81,16 @@ private String[] getSubkeys(String originalKey) {
         }
         String[] subKeys = new String[16];
         String initialPermutedKey = permutedKey.toString();
-        String C0 = initialPermutedKey.substring(0, 28);
-        String D0 = initialPermutedKey.substring(28);
+        String c0 = initialPermutedKey.substring(0, 28);
+        String 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(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;
+            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;
         }
 
         // Let us shrink the keys to 48 bits (well, characters here) using pc2
@@ -169,18 +169,18 @@ private String encryptBlock(String message, String[] keys) {
         for (i = 0; i < 64; i++) {
             permutedMessage.append(message.charAt(IP[i] - 1));
         }
-        String L0 = permutedMessage.substring(0, 32);
-        String R0 = permutedMessage.substring(32);
+        String e0 = permutedMessage.substring(0, 32);
+        String f0 = permutedMessage.substring(32);
 
         // Iterate 16 times
         for (i = 0; i < 16; i++) {
-            String Ln = R0; // Previous Right block
-            String Rn = xOR(L0, feistel(R0, keys[i]));
-            L0 = Ln;
-            R0 = Rn;
+            String eN = f0; // Previous Right block
+            String fN = xOR(e0, feistel(f0, keys[i]));
+            e0 = eN;
+            f0 = fN;
         }
 
-        String combinedBlock = R0 + L0; // Reverse the 16th block
+        String combinedBlock = f0 + e0; // Reverse the 16th block
         permutedMessage.setLength(0);
         for (i = 0; i < 64; i++) {
             permutedMessage.append(combinedBlock.charAt(IP_INVERSE[i] - 1));

src/main/java/com/thealgorithms/ciphers/HillCipher.java

@@ -35,7 +35,7 @@ static void encrypt(String message) {
         validateDeterminant(keyMatrix, matrixSize);
 
         int[][] messageVector = new int[matrixSize][1];
-        String CipherText = "";
+        String cipherText = "";
         int[][] cipherMatrix = new int[matrixSize][1];
         int j = 0;
         while (j < message.length()) {
@@ -60,10 +60,10 @@ static void encrypt(String message) {
                 cipherMatrix[i][0] = cipherMatrix[i][0] % 26;
             }
             for (i = 0; i < matrixSize; i++) {
-                CipherText += (char) (cipherMatrix[i][0] + 65);
+                cipherText += (char) (cipherMatrix[i][0] + 65);
             }
         }
-        System.out.println("Ciphertext: " + CipherText);
+        System.out.println("Ciphertext: " + cipherText);
     }
 
     // Following function decrypts a message
@@ -84,7 +84,7 @@ static void decrypt(String message) {
 
         // solving for the required plaintext message
         int[][] messageVector = new int[n][1];
-        String PlainText = "";
+        String plainText = "";
         int[][] plainMatrix = new int[n][1];
         int j = 0;
         while (j < message.length()) {
@@ -109,10 +109,10 @@ static void decrypt(String message) {
                 plainMatrix[i][0] = plainMatrix[i][0] % 26;
             }
             for (i = 0; i < n; i++) {
-                PlainText += (char) (plainMatrix[i][0] + 65);
+                plainText += (char) (plainMatrix[i][0] + 65);
             }
         }
-        System.out.println("Plaintext: " + PlainText);
+        System.out.println("Plaintext: " + plainText);
     }
 
     // Determinant calculator

src/main/java/com/thealgorithms/conversions/HexaDecimalToDecimal.java

@@ -20,20 +20,20 @@ public static int getHexaToDec(String hex) {
 
     // Main method gets the hexadecimal input from user and converts it into Decimal output.
     public static void main(String[] args) {
-        String hexa_Input;
-        int dec_output;
+        String hexaInput;
+        int decOutput;
         Scanner scan = new Scanner(System.in);
 
         System.out.print("Enter Hexadecimal Number : ");
-        hexa_Input = scan.nextLine();
+        hexaInput = scan.nextLine();
 
         // convert hexadecimal to decimal
-        dec_output = getHexaToDec(hexa_Input);
+        decOutput = getHexaToDec(hexaInput);
         /*
     Pass the string to the getHexaToDec function
-    and it returns the decimal form in the variable dec_output.
+    and it returns the decimal form in the variable decOutput.
          */
-        System.out.println("Number in Decimal: " + dec_output);
+        System.out.println("Number in Decimal: " + decOutput);
         scan.close();
     }
 }

src/main/java/com/thealgorithms/datastructures/graphs/BipartiteGrapfDFS.java

@@ -54,23 +54,23 @@ public static void main(String[] args) throws IOException {
         BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
         int t = Integer.parseInt(read.readLine().trim());
         while (t-- > 0) {
-            String[] S = read.readLine().trim().split(" ");
-            int V = Integer.parseInt(S[0]);
-            int E = Integer.parseInt(S[1]);
+            String[] str1 = read.readLine().trim().split(" ");
+            int numVertices = Integer.parseInt(str1[0]);
+            int numEdges = Integer.parseInt(str1[1]);
 
             ArrayList<ArrayList<Integer>> adj = new ArrayList<>();
-            for (int i = 0; i < V; i++) {
+            for (int i = 0; i < numVertices; i++) {
                 adj.add(new ArrayList<>());
             }
-            for (int i = 0; i < E; i++) {
-                String[] s = read.readLine().trim().split(" ");
-                int u = Integer.parseInt(s[0]);
-                int v = Integer.parseInt(s[1]);
-                adj.get(u).add(v);
-                adj.get(v).add(u);
+            for (int i = 0; i < numEdges; i++) {
+                String[] str2 = read.readLine().trim().split(" ");
+                int vertexU = Integer.parseInt(str2[0]);
+                int vertexV = Integer.parseInt(str2[1]);
+                adj.get(vertexU).add(vertexV);
+                adj.get(vertexV).add(vertexU);
             }
 
-            boolean ans = isBipartite(V, adj);
+            boolean ans = isBipartite(numVertices, adj);
             if (ans) {
                 System.out.println("YES");
             } else {

src/main/java/com/thealgorithms/datastructures/graphs/DIJSKSTRAS_ALGORITHM.java

@@ -8,18 +8,18 @@ class dijkstras {
 
     int k = 9;
 
-    int minDist(int[] dist, Boolean[] Set) {
+    int minDist(int[] dist, Boolean[] set) {
         int min = Integer.MAX_VALUE;
-        int min_index = -1;
+        int minIndex = -1;
 
         for (int r = 0; r < k; r++) {
-            if (!Set[r] && dist[r] <= min) {
+            if (!set[r] && dist[r] <= min) {
                 min = dist[r];
-                min_index = r;
+                minIndex = r;
             }
         }
 
-        return min_index;
+        return minIndex;
     }
 
     void print(int[] dist) {
@@ -31,22 +31,22 @@ void print(int[] dist) {
 
     void dijkstra(int[][] graph, int src) {
         int[] dist = new int[k];
-        Boolean[] Set = new Boolean[k];
+        Boolean[] set = new Boolean[k];
 
         for (int i = 0; i < k; i++) {
             dist[i] = Integer.MAX_VALUE;
-            Set[i] = Boolean.FALSE;
+            set[i] = Boolean.FALSE;
         }
 
         dist[src] = 0;
 
         for (int c = 0; c < k - 1; c++) {
-            int u = minDist(dist, Set);
+            int u = minDist(dist, set);
 
-            Set[u] = Boolean.TRUE;
+            set[u] = Boolean.TRUE;
 
             for (int v = 0; v < k; v++) {
-                if (!Set[v] && graph[u][v] != 0 && dist[u] != Integer.MAX_VALUE && dist[u] + graph[u][v] < dist[v]) {
+                if (!set[v] && graph[u][v] != 0 && dist[u] != Integer.MAX_VALUE && dist[u] + graph[u][v] < dist[v]) {
                     dist[v] = dist[u] + graph[u][v];
                 }
             }

src/main/java/com/thealgorithms/datastructures/graphs/PrimMST.java

@@ -15,16 +15,16 @@ class PrimMST {
     int minKey(int[] key, Boolean[] mstSet) {
         // Initialize min value
         int min = Integer.MAX_VALUE;
-        int min_index = -1;
+        int minIndex = -1;
 
         for (int v = 0; v < V; v++) {
             if (!mstSet[v] && key[v] < min) {
                 min = key[v];
-                min_index = v;
+                minIndex = v;
             }
         }
 
-        return min_index;
+        return minIndex;
     }
 
     // A utility function to print the constructed MST stored in

src/main/java/com/thealgorithms/datastructures/hashmap/hashing/Main.java

@@ -11,7 +11,7 @@ public static void main(String[] args) {
         int key;
 
         HashMap h = new HashMap(7);
-        Scanner In = new Scanner(System.in);
+        Scanner scan = new Scanner(System.in);
 
         while (true) {
             System.out.println("Enter your Choice :");
@@ -20,18 +20,18 @@ public static void main(String[] args) {
             System.out.println("3. Print Table");
             System.out.println("4. Exit");
 
-            choice = In.nextInt();
+            choice = scan.nextInt();
 
             switch (choice) {
             case 1: {
                 System.out.println("Enter the Key: ");
-                key = In.nextInt();
+                key = scan.nextInt();
                 h.insertHash(key);
                 break;
             }
             case 2: {
                 System.out.println("Enter the Key delete:  ");
-                key = In.nextInt();
+                key = scan.nextInt();
                 h.deleteHash(key);
                 break;
             }
@@ -41,7 +41,7 @@ public static void main(String[] args) {
                 break;
             }
             case 4: {
-                In.close();
+                scan.close();
                 return;
             }
             default: {

src/main/java/com/thealgorithms/datastructures/hashmap/hashing/MainCuckooHashing.java

@@ -11,7 +11,7 @@ public static void main(String[] args) {
         int key;
 
         HashMapCuckooHashing h = new HashMapCuckooHashing(7);
-        Scanner In = new Scanner(System.in);
+        Scanner scan = new Scanner(System.in);
 
         while (true) {
             System.out.println("_________________________");
@@ -24,18 +24,18 @@ public static void main(String[] args) {
             System.out.println("6. Check load factor");
             System.out.println("7. Rehash Current Table");
 
-            choice = In.nextInt();
+            choice = scan.nextInt();
 
             switch (choice) {
             case 1: {
                 System.out.println("Enter the Key: ");
-                key = In.nextInt();
+                key = scan.nextInt();
                 h.insertKey2HashTable(key);
                 break;
             }
             case 2: {
                 System.out.println("Enter the Key delete:  ");
-                key = In.nextInt();
+                key = scan.nextInt();
                 h.deleteKeyFromHashTable(key);
                 break;
             }
@@ -45,12 +45,12 @@ public static void main(String[] args) {
                 break;
             }
             case 4: {
-                In.close();
+                scan.close();
                 return;
             }
             case 5: {
                 System.out.println("Enter the Key to find and print:  ");
-                key = In.nextInt();
+                key = scan.nextInt();
                 System.out.println("Key: " + key + " is at index: " + h.findKeyInTable(key) + "\n");
                 break;
             }