Fix LFUCache (TheAlgorithms#3847)

yuluo-yx · web-flow · commit b14f55096df0 · 2023-01-15T11:28:16.000+02:00
diff --git a/src/main/java/com/thealgorithms/datastructures/caches/LFUCache.java b/src/main/java/com/thealgorithms/datastructures/caches/LFUCache.java
@@ -101,7 +101,7 @@ private void addNodeWithUpdatedFrequency(Node node) {
                         node.next = temp;
                         node.previous = temp.previous;
                         temp.previous.next = node;
-                        node.previous = temp.previous;
+                        temp.previous = node;
                         break;
                     }
                 } else {
diff --git a/src/test/java/com/thealgorithms/datastructures/caches/LFUCacheTest.java b/src/test/java/com/thealgorithms/datastructures/caches/LFUCacheTest.java
@@ -61,4 +61,22 @@ void testLFUCacheWithStringValueShouldPass() {
         assertEquals(null, lfuCache.get(2));
         assertEquals("Zeta", lfuCache.get(7));
     }
+
+    /**
+     * test addNodeWithUpdatedFrequency method
+     * @author yuluo
+     */
+    @Test
+    void testAddNodeWithUpdatedFrequency() {
+        LFUCache<Integer, String> lfuCache = new LFUCache<>(3);
+        lfuCache.put(1, "beijing");
+        lfuCache.put(2, "shanghai");
+        lfuCache.put(3, "gansu");
+
+        assertEquals("beijing", lfuCache.get(1));
+
+        lfuCache.put(1, "shanxi");
+
+        assertEquals("shanxi", lfuCache.get(1));
+    }
 }

Original file line number	Diff line number	Diff line change
`@@ -101,7 +101,7 @@ private void addNodeWithUpdatedFrequency(Node node) {`
`101`	`101`	`node.next = temp;`
`102`	`102`	`node.previous = temp.previous;`
`103`	`103`	`temp.previous.next = node;`
`104`		`- node.previous = temp.previous;`
	`104`	`+ temp.previous = node;`
`105`	`105`	`break;`
`106`	`106`	`}`
`107`	`107`	`} else {`