A*算法属于一种启发式搜索。它扩展结点的次序类似于广度优先搜索，但不同的是每生成一个子结点需要计算估价函数F，以估算起始结点到该结点的代价及它到达目标结点的代价的和；每当扩展结点时，总是在所有待扩展结点中选择具有最小F值的结点作为扩展对象，以便使搜索尽量沿最有希望的方向进行。 -A * algorithm is a heuristic search. It extended node in the order of priority similar to the breadth of search, but in every generation is a sub-node calculated valuation function F, to estimate initial node to the node, the price and it arrived at the target node, and the price; Whenever expansion node, the question has always extended to all nodes with the smallest choosing F value of the node as expansion targets, in order to search as far as possible along the most promising direction.