Dijkstra's algorithm. It picks the unvisited vertex with the lowest-distance, calculates the distance through it to each unvisited neighbor, and updates the neighbor's distance if smaller. Mark visited (set to red) when done with neighbors.
Here is to a bit of solidarity with the people of Boston following the attack on the Boston marathon yesterday. Such a despicable, cruel crime met with honor courage and self sacrifice by those immediately effected.
I've been thinking about Earth. Typically we think of the Earth as being a perfect sphere as represented by those silly globes from grade school. In reality, due to concentrations of magma, mountains and deep sea trenches, the Earth is anything but a perfect sphere. Not only does this distort our concept of a perfectly spherical planet, but it also distorts the Earth's gravitational field, causing regional anomalies. Visualization helps. Here are a few images of the Earth's gravitational anomalies in relief: