Merge branch 'master' into refactor/ReverseStackUsingRecursion

siriak · web-flow · commit ae2cabd71c3b · 2024-08-25T10:07:44.000+03:00
diff --git a/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java b/src/main/java/com/thealgorithms/dynamicprogramming/FordFulkerson.java
@@ -2,76 +2,54 @@
 
 import java.util.LinkedList;
 import java.util.Queue;
-import java.util.Vector;
 
 public final class FordFulkerson {
-    private FordFulkerson() {
-    }
-
-    static final int INF = 987654321;
-    // edges
-    static int vertexCount;
-    static int[][] capacity;
-    static int[][] flow;
+    private static final int INF = Integer.MAX_VALUE;
 
-    public static void main(String[] args) {
-        System.out.println("Vertex Count : 6");
-        vertexCount = 6;
-        capacity = new int[vertexCount][vertexCount];
-
-        capacity[0][1] = 12;
-        capacity[0][3] = 13;
-        capacity[1][2] = 10;
-        capacity[2][3] = 13;
-        capacity[2][4] = 3;
-        capacity[2][5] = 15;
-        capacity[3][2] = 7;
-        capacity[3][4] = 15;
-        capacity[4][5] = 17;
-
-        System.out.println("Max capacity in networkFlow : " + networkFlow(0, 5));
+    private FordFulkerson() {
     }
 
-    private static int networkFlow(int source, int sink) {
-        flow = new int[vertexCount][vertexCount];
+    public static int networkFlow(int vertexCount, int[][] capacity, int[][] flow, int source, int sink) {
         int totalFlow = 0;
+
         while (true) {
-            Vector<Integer> parent = new Vector<>(vertexCount);
-            for (int i = 0; i < vertexCount; i++) {
-                parent.add(-1);
-            }
-            Queue<Integer> q = new LinkedList<>();
-            parent.set(source, source);
-            q.add(source);
-            while (!q.isEmpty() && parent.get(sink) == -1) {
-                int here = q.peek();
-                q.poll();
-                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);
+            int[] parent = new int[vertexCount];
+            boolean[] visited = new boolean[vertexCount];
+            Queue<Integer> queue = new LinkedList<>();
+
+            queue.add(source);
+            visited[source] = true;
+            parent[source] = -1;
+
+            while (!queue.isEmpty() && !visited[sink]) {
+                int current = queue.poll();
+
+                for (int next = 0; next < vertexCount; next++) {
+                    if (!visited[next] && capacity[current][next] - flow[current][next] > 0) {
+                        queue.add(next);
+                        visited[next] = true;
+                        parent[next] = current;
                     }
                 }
             }
-            if (parent.get(sink) == -1) {
-                break;
+
+            if (!visited[sink]) {
+                break; // No more augmenting paths
             }
 
-            int amount = INF;
-            String printer = "path : ";
-            StringBuilder sb = new StringBuilder();
-            for (int p = sink; p != source; p = parent.get(p)) {
-                amount = Math.min(capacity[parent.get(p)][p] - flow[parent.get(p)][p], amount);
-                sb.append(p + "-");
+            int pathFlow = INF;
+            for (int v = sink; v != source; v = parent[v]) {
+                int u = parent[v];
+                pathFlow = Math.min(pathFlow, capacity[u][v] - flow[u][v]);
             }
-            sb.append(source);
-            for (int p = sink; p != source; p = parent.get(p)) {
-                flow[parent.get(p)][p] += amount;
-                flow[p][parent.get(p)] -= amount;
+
+            for (int v = sink; v != source; v = parent[v]) {
+                int u = parent[v];
+                flow[u][v] += pathFlow;
+                flow[v][u] -= pathFlow;
             }
-            totalFlow += amount;
-            printer += sb.reverse() + " / max flow : " + totalFlow;
-            System.out.println(printer);
+
+            totalFlow += pathFlow;
         }
 
         return totalFlow;
diff --git a/src/main/java/com/thealgorithms/others/TwoPointers.java b/src/main/java/com/thealgorithms/others/TwoPointers.java
@@ -1,39 +1,33 @@
 package com.thealgorithms.others;
 
-import java.util.Arrays;
-
 /**
- * The two pointer technique is a useful tool to utilize when searching for
+ * The two-pointer technique is a useful tool to utilize when searching for
  * pairs in a sorted array.
  *
  * <p>
- * link: https://www.geeksforgeeks.org/two-pointers-technique/
+ * Link: https://www.geeksforgeeks.org/two-pointers-technique/
  */
 final class TwoPointers {
     private TwoPointers() {
     }
 
     /**
-     * Given a sorted array arr (sorted in ascending order). Find if there
-     * exists any pair of elements such that their sum is equal to key.
+     * Given a sorted array arr (sorted in ascending order), find if there exists
+     * any pair of elements such that their sum is equal to the key.
      *
-     * @param arr the array contains elements
+     * @param arr the array containing elements (must be sorted in ascending order)
      * @param key the number to search
-     * @return {@code true} if there exists a pair of elements, {@code false}
-     * otherwise.
+     * @return {@code true} if there exists a pair of elements, {@code false} otherwise.
      */
     public static boolean isPairedSum(int[] arr, int key) {
-        /* array sorting is necessary for this algorithm to function correctly */
-        Arrays.sort(arr);
-        int i = 0;
-        /* index of first element */
-        int j = arr.length - 1;
-        /* index of last element */
+        int i = 0; // index of the first element
+        int j = arr.length - 1; // index of the last element
 
         while (i < j) {
-            if (arr[i] + arr[j] == key) {
+            int sum = arr[i] + arr[j];
+            if (sum == key) {
                 return true;
-            } else if (arr[i] + arr[j] < key) {
+            } else if (sum < key) {
                 i++;
             } else {
                 j--;
diff --git a/src/test/java/com/thealgorithms/dynamicprogramming/FordFulkersonTest.java b/src/test/java/com/thealgorithms/dynamicprogramming/FordFulkersonTest.java
@@ -0,0 +1,94 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class FordFulkersonTest {
+    @Test
+    public void testMaxFlow() {
+        int vertexCount = 6;
+        int[][] capacity = new int[vertexCount][vertexCount];
+        int[][] flow = new int[vertexCount][vertexCount];
+
+        // Setting up the capacity graph
+        capacity[0][1] = 12;
+        capacity[0][3] = 13;
+        capacity[1][2] = 10;
+        capacity[2][3] = 13;
+        capacity[2][4] = 3;
+        capacity[2][5] = 15;
+        capacity[3][2] = 7;
+        capacity[3][4] = 15;
+        capacity[4][5] = 17;
+
+        int maxFlow = FordFulkerson.networkFlow(vertexCount, capacity, flow, 0, 5);
+        assertEquals(23, maxFlow);
+    }
+
+    @Test
+    public void testNoFlow() {
+        int vertexCount = 6;
+        int[][] capacity = new int[vertexCount][vertexCount];
+        int[][] flow = new int[vertexCount][vertexCount];
+
+        // No connections between source and sink
+        capacity[0][1] = 10;
+        capacity[2][3] = 10;
+
+        int maxFlow = FordFulkerson.networkFlow(vertexCount, capacity, flow, 1, 4);
+        assertEquals(0, maxFlow);
+    }
+
+    @Test
+    public void testSinglePath() {
+        int vertexCount = 6;
+        int[][] capacity = new int[vertexCount][vertexCount];
+        int[][] flow = new int[vertexCount][vertexCount];
+
+        // Setting up a single path from source to sink
+        capacity[0][1] = 5;
+        capacity[1][2] = 5;
+        capacity[2][3] = 5;
+        capacity[3][4] = 5;
+        capacity[4][5] = 5;
+
+        int maxFlow = FordFulkerson.networkFlow(vertexCount, capacity, flow, 0, 5);
+        assertEquals(5, maxFlow);
+    }
+
+    @Test
+    public void testParallelPaths() {
+        int vertexCount = 4;
+        int[][] capacity = new int[vertexCount][vertexCount];
+        int[][] flow = new int[vertexCount][vertexCount];
+
+        // Setting up parallel paths from source to sink
+        capacity[0][1] = 10;
+        capacity[0][2] = 10;
+        capacity[1][3] = 10;
+        capacity[2][3] = 10;
+
+        int maxFlow = FordFulkerson.networkFlow(vertexCount, capacity, flow, 0, 3);
+        assertEquals(20, maxFlow);
+    }
+
+    @Test
+    public void testComplexNetwork() {
+        int vertexCount = 5;
+        int[][] capacity = new int[vertexCount][vertexCount];
+        int[][] flow = new int[vertexCount][vertexCount];
+
+        // Complex network
+        capacity[0][1] = 10;
+        capacity[0][2] = 10;
+        capacity[1][3] = 4;
+        capacity[1][4] = 8;
+        capacity[2][4] = 9;
+        capacity[3][2] = 6;
+        capacity[3][4] = 10;
+
+        int maxFlow = FordFulkerson.networkFlow(vertexCount, capacity, flow, 0, 4);
+        assertEquals(19, maxFlow);
+    }
+}
diff --git a/src/test/java/com/thealgorithms/maths/PrimeFactorizationTest.java b/src/test/java/com/thealgorithms/maths/PrimeFactorizationTest.java
@@ -1,36 +1,32 @@
 package com.thealgorithms.maths;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.List;
-import org.junit.jupiter.api.Test;
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 
 class PrimeFactorizationTest {
 
-    @Test
-    void testpFactorsMustReturnEmptyList() {
-        // given
-        int n = 0;
-
-        // then
-        assertTrue(PrimeFactorization.pfactors(n).isEmpty());
+    @ParameterizedTest
+    @MethodSource("provideNumbersAndFactors")
+    void testPrimeFactorization(int number, List<Integer> expectedFactors) {
+        assertEquals(expectedFactors, PrimeFactorization.pfactors(number), "Prime factors for number: " + number);
     }
 
-    @Test
-    void testpFactorsMustReturnNonEmptyList() {
-        // given
-        int n = 198;
-        int expectedListSize = 4;
+    @ParameterizedTest
+    @MethodSource("provideNumbersAndSizes")
+    void testPrimeFactorsSize(int number, int expectedSize) {
+        assertEquals(expectedSize, PrimeFactorization.pfactors(number).size(), "Size of prime factors list for number: " + number);
+    }
 
-        // when
-        List<Integer> actualResultList = PrimeFactorization.pfactors(n);
+    private static Stream<Arguments> provideNumbersAndFactors() {
+        return Stream.of(Arguments.of(0, List.of()), Arguments.of(1, List.of()), Arguments.of(2, List.of(2)), Arguments.of(3, List.of(3)), Arguments.of(4, List.of(2, 2)), Arguments.of(18, List.of(2, 3, 3)), Arguments.of(100, List.of(2, 2, 5, 5)), Arguments.of(198, List.of(2, 3, 3, 11)));
+    }
 
-        // then
-        assertEquals(expectedListSize, actualResultList.size());
-        assertEquals(2, actualResultList.get(0));
-        assertEquals(3, actualResultList.get(1));
-        assertEquals(3, actualResultList.get(2));
-        assertEquals(11, actualResultList.get(3));
+    private static Stream<Arguments> provideNumbersAndSizes() {
+        return Stream.of(Arguments.of(2, 1), Arguments.of(3, 1), Arguments.of(4, 2), Arguments.of(18, 3), Arguments.of(100, 4), Arguments.of(198, 4));
     }
 }
diff --git a/src/test/java/com/thealgorithms/maths/ReverseNumberTest.java b/src/test/java/com/thealgorithms/maths/ReverseNumberTest.java
@@ -3,27 +3,21 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-import java.util.HashMap;
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.ValueSource;
 
 public class ReverseNumberTest {
 
-    @Test
-    public void testReverseNumber() {
-        HashMap<Integer, Integer> testCases = new HashMap<>();
-        testCases.put(0, 0);
-        testCases.put(1, 1);
-        testCases.put(10, 1);
-        testCases.put(123, 321);
-        testCases.put(7890, 987);
-
-        for (final var tc : testCases.entrySet()) {
-            assertEquals(ReverseNumber.reverseNumber(tc.getKey()), tc.getValue());
-        }
+    @ParameterizedTest
+    @CsvSource({"0, 0", "1, 1", "10, 1", "123, 321", "7890, 987"})
+    public void testReverseNumber(int input, int expected) {
+        assertEquals(expected, ReverseNumber.reverseNumber(input));
     }
 
-    @Test
-    public void testReverseNumberThrowsExceptionForNegativeInput() {
-        assertThrows(IllegalArgumentException.class, () -> ReverseNumber.reverseNumber(-1));
+    @ParameterizedTest
+    @ValueSource(ints = {-1, -123, -7890})
+    public void testReverseNumberThrowsExceptionForNegativeInput(int input) {
+        assertThrows(IllegalArgumentException.class, () -> ReverseNumber.reverseNumber(input));
     }
 }
diff --git a/src/test/java/com/thealgorithms/others/TwoPointersTest.java b/src/test/java/com/thealgorithms/others/TwoPointersTest.java
