人工智能中的经典算法之一。对问题的多个分支选择一支进行探索，当探索到某一步时，发现原先选择并不优或达不到目标，就退回一步重新选择

回溯法适合用栈实现。探索过程当中入栈，退栈时返回分支选择的现场

-One of the classic algorithms in artificial intelligence. Multiple branches of the problem, choose one to explore, explore a step that the original selection is not excellent or reach the goal, you step back and re-retrospective method is suitable to use the stack to achieve. Exploring the process, stack, stack retreat back to the site of the branch selection