Add calculateXP function

src/lib/bd.ts

@@ -0,0 +1,20 @@
+export const calculateXP = (
+  normalBerries: number,
+  poisonBerries: number,
+  slowBerries: number,
+  ultraBerries: number,
+  speedyBerries: number,
+  coinBerries: number
+): number => {
+  let totalXp: number = 0
+
+  totalXp += normalBerries
+  totalXp -= poisonBerries
+  totalXp -= slowBerries
+  totalXp += ultraBerries * 5
+  totalXp += speedyBerries * 10
+  totalXp += coinBerries * 10
+
+  if (totalXp < 0n) totalXp = 0
+  return totalXp
+}