Add Breadth First Search (TheAlgorithms#2801)

Co-authored-by: xzero <[email protected]>
Co-authored-by: Andrii Siriak <[email protected]>

Author: 3 people

Searches/BreadthFirstSearch.java

@@ -0,0 +1,80 @@
+package Searches;
+
+import Searches.DepthFirstSearch.Node;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+
+/**
+ * @author:  caos321
+ * @date:    31 October 2021 (Sunday)
+ */
+public class BreadthFirstSearch {
+
+    public static Optional<Node> search(final Node node, final String name) {
+        if (node.getName().equals(name)) {
+            return Optional.of(node);
+        }
+
+        List<Node> queue = new ArrayList<>(node.getSubNodes());
+
+        while(!queue.isEmpty()) {
+            final Node current = queue.get(0);
+
+            if(current.getName().equals(name)) {
+                return Optional.of(current);
+            }
+
+            queue.addAll(current.getSubNodes());
+
+            queue.remove(0);
+        }
+
+        return Optional.empty();
+    }
+
+    public static void assertThat(final Object actual, final Object expected) {
+        if (!Objects.equals(actual, expected)) {
+            throw new AssertionError(String.format("expected=%s but was actual=%s", expected, actual));
+        }
+    }
+
+    public static void main(final String[] args) {
+        final Node rootNode = new Node("A", List.of(
+                new Node("B", List.of(new Node("D"), new Node("F", List.of(
+                        new Node("H"), new Node("I")
+                )))),
+                new Node("C", List.of(new Node("G"))),
+                new Node("E")
+        ));
+
+        {
+            final String expected = "I";
+
+            final Node result = search(rootNode, expected)
+                    .orElseThrow(() -> new AssertionError("Node not found!"));
+
+            assertThat(result.getName(), expected);
+        }
+
+        {
+            final String expected = "G";
+
+            final Node result = search(rootNode, expected)
+                    .orElseThrow(() -> new AssertionError("Node not found!"));
+
+            assertThat(result.getName(), expected);
+        }
+
+        {
+            final String expected = "E";
+
+            final Node result = search(rootNode, expected)
+                    .orElseThrow(() -> new AssertionError("Node not found!"));
+
+            assertThat(result.getName(), expected);
+        }
+    }
+}