adding old solved challenges

BirdsMigration/\

@@ -0,0 +1,35 @@
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class BirdsMigration {
+  public static void main(String[] args) {
+
+    List<Integer> BirdType = new ArrayList<>();
+    BirdType.add(1);
+    BirdType.add(3);
+    BirdType.add(3);
+    BirdType.add(2);
+    BirdType.add(2);
+    BirdType.add(2);
+
+    System.out.println(smallestID(BirdType));
+
+  }
+
+  private static int smallestID(List<Integer> birds) {
+    int[] birdsTypeId = new int[6];
+    int max = 0;
+
+    for (int bird : birds) {
+      birdsTypeId[bird]++;
+      max = Math.max(max, birdsTypeId[bird]);
+    }
+    for (int i = 0; i < birdsTypeId.length; i++) {
+      if (birdsTypeId[i] == max) {
+        return i;
+      }
+    }
+    return 0;
+  }
+}