Overlapping condition changed

Overlapping happens not when centers of circular bodies are in the same point, but when the distance between them is smaller than the sum of their radii.

Author: kvadrik

src/main/java/com/thealgorithms/physics/ElasticCollision2D.java

@@ -41,7 +41,7 @@ public static void resolveCollision(Body a, Body b) {
         double dy = b.y - a.y;
         double dist = Math.hypot(dx, dy);
 
-        if (dist == 0) {
+        if (dist < a.radius + b.radius) {
             return; // overlapping
         }