Masyu

Masyu is played on a grid of squares. Some cells contain white or black circles. The goal is to draw a single continuous non-intersecting loop that properly passes through all circled cells. The loop must enter each cell it passes through from the center of one of its four sides and exit from a different side. Sometimes, the circles are on the corners between squares and you draw lines along the edges instead.

1. White circles must be traveled straight through, but the loop must turn in the previous and/or next cell in its path.
2. Black circles must be turned upon, but the loop must travel straight through the next and previous cells in its path.