A* Search

It is best-known form of Best First search. It avoids expanding paths that are already expensive, but expands most promising paths first.
f(n) = g(n) + h(n), where
• g(n) the cost (so far) to reach the node
• h(n) estimated cost to get from the node to the goal
• f(n) estimated total cost of path through n to goal. It is implemented using priority queue by increasing f(n).