Updating the file to add the GaleShapley algorithm in the greedy algorithms package.

Author: BKarthik7

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

@@ -0,0 +1,45 @@
+package com.thealgorithms.greedyalgorithms;
+
+import java.util.HashMap;
+import java.util.LinkedList;
+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);
+
+            if (manPref == null) {
+                continue;
+            }
+
+            String woman = manPref.poll();
+            String fiance = engagements.get(woman);
+
+            if (fiance == null) {
+                engagements.put(woman, man);
+            } else {
+                LinkedList<String> womanPrefList = womenPrefs.get(woman);
+
+                if (womanPrefList == null) {
+                    continue;
+                }
+
+                if (womanPrefList.indexOf(man) < womanPrefList.indexOf(fiance)) {
+                    engagements.put(woman, man);
+                    freeMen.add(fiance);
+                } else {
+                    freeMen.add(man);
+                }
+            }
+        }
+
+        return engagements;
+    }
+}