Update GaleShapleyTest.java

Author: BKarthik7

src/test/java/com/thealgorithms/greedyalgorithms/GaleShapleyTest.java

@@ -1,53 +1,72 @@
 package com.thealgorithms.greedyalgorithms;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import java.util.HashMap;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Map;
-import java.util.Queue;
-
-public class GaleShapley {
-
-    public static Map<String, String> stableMatch(Map<String, LinkedList<String>> womenPrefs, 
-                                                  Map<String, LinkedList<String>> menPrefs) {
-        Map<String, String> engagements = new HashMap<>();
-        Queue<String> freeMen = new LinkedList<>(menPrefs.keySet());
-
-        while (!freeMen.isEmpty()) {
-            String man = freeMen.poll();
-            LinkedList<String> manPref = menPrefs.get(man);
-
-            // Ensure manPref is not null before proceeding
-            if (manPref == null) {
-                continue;
-            }
-
-            // Propose to the first woman in the man's preference list
-            String woman = manPref.poll();
-            String fiance = engagements.get(woman);
-
-            if (fiance == null) {
-                // Woman is free, engage the man and woman
-                engagements.put(woman, man);
-            } else {
-                // Woman is already engaged, check if she prefers this man over her current fiance
-                LinkedList<String> womanPrefList = womenPrefs.get(woman);
-
-                // Ensure womanPrefList is not null before comparing
-                if (womanPrefList == null) {
-                    continue;
-                }
-
-                // If the woman prefers the current man over her current fiance
-                if (womanPrefList.indexOf(man) < womanPrefList.indexOf(fiance)) {
-                    engagements.put(woman, man);
-                    freeMen.add(fiance); // Previous fiance becomes free
-                } else {
-                    // Woman stays with her current fiance, man remains free
-                    freeMen.add(man);
-                }
-            }
-        }
-
-        return engagements;
+import org.junit.jupiter.api.Test;
+
+public class GaleShapleyTest {
+
+    @Test
+    public void testStableMatch() {
+        Map<String, LinkedList<String>> womenPrefs = new HashMap<>();
+        womenPrefs.put("A", new LinkedList<>(List.of("X", "Y", "Z")));
+        womenPrefs.put("B", new LinkedList<>(List.of("Y", "X", "Z")));
+        womenPrefs.put("C", new LinkedList<>(List.of("X", "Y", "Z")));
+
+        Map<String, LinkedList<String>> menPrefs = new HashMap<>();
+        menPrefs.put("X", new LinkedList<>(List.of("A", "B", "C")));
+        menPrefs.put("Y", new LinkedList<>(List.of("B", "A", "C")));
+        menPrefs.put("Z", new LinkedList<>(List.of("A", "B", "C")));
+
+        Map<String, String> result = GaleShapley.stableMatch(womenPrefs, menPrefs);
+
+        Map<String, String> expected = new HashMap<>();
+        expected.put("A", "X");
+        expected.put("B", "Y");
+        expected.put("C", "Z");
+
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void testSinglePair() {
+        Map<String, LinkedList<String>> womenPrefs = new HashMap<>();
+        womenPrefs.put("A", new LinkedList<>(List.of("X")));
+
+        Map<String, LinkedList<String>> menPrefs = new HashMap<>();
+        menPrefs.put("X", new LinkedList<>(List.of("A")));
+
+        Map<String, String> result = GaleShapley.stableMatch(womenPrefs, menPrefs);
+
+        Map<String, String> expected = new HashMap<>();
+        expected.put("A", "X");
+
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void testEqualPreferences() {
+        Map<String, LinkedList<String>> womenPrefs = new HashMap<>();
+        womenPrefs.put("A", new LinkedList<>(List.of("X", "Y", "Z")));
+        womenPrefs.put("B", new LinkedList<>(List.of("X", "Y", "Z")));
+        womenPrefs.put("C", new LinkedList<>(List.of("X", "Y", "Z")));
+
+        Map<String, LinkedList<String>> menPrefs = new HashMap<>();
+        menPrefs.put("X", new LinkedList<>(List.of("A", "B", "C")));
+        menPrefs.put("Y", new LinkedList<>(List.of("A", "B", "C")));
+        menPrefs.put("Z", new LinkedList<>(List.of("A", "B", "C")));
+
+        Map<String, String> result = GaleShapley.stableMatch(womenPrefs, menPrefs);
+
+        Map<String, String> expected = new HashMap<>();
+        expected.put("A", "X");
+        expected.put("B", "Y");
+        expected.put("C", "Z");
+
+        assertEquals(expected, result);
     }
 }