a star things

370/notes/a-star.md

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+# A\* Pathfinding
+
+There are 3 main values usedd in reference to A\*: 
+
+```
+f = how promisiing a new location is
+g = distance from origin
+h = estimate distance to goal
+f = g + h
+```
+
+For a grid space our `h` is calculated by two straight shots to the goal from the current location(ignore barriers).
+The grid space `g` value is basiccally the number of steps we've taken from the origin.
+We maintain a list of potential nodes only, so if one of the seeking nodes gets us stuck we can freely remove that, because it succs.
+
+# Time & Space Commplexities
+
+## Best-First Search
+
+Time: O(VlogV + E)
+
+## Dijkstra's
+
+O(V)
+
+## A\*
+O(V^2 = E)