相关疑难解决方法(0)

这两个代码片段之间有什么区别？使用type():

import types

if type(a) is types.DictType:
    do_something()
if type(b) in types.StringTypes:
    do_something_else()

使用isinstance():

if isinstance(a, dict):
    do_something()
if isinstance(b, str) or isinstance(b, unicode):
    do_something_else()

Peter Norvig 通过结合确定性逻辑运算和可能解决方案的智能遍历,撰写了一篇描述解决数独难题的程序的文章,即使是最困难的难题.后者是递归完成的; 这是该功能(来源):

def search(values):
    "Using depth-first search and propagation, try all possible values."
    if values is False:
        return False ## Failed earlier
    if all( len( values[s]) == 1 for s in squares): 
        return values ## Solved!
    ## Chose the unfilled square s with the fewest possibilities
    _,s = min( (len( values[s]), s) 
                for s in squares 
                if len(values[s]) > 1
            )
    return some( search( assign( values.copy(), s, d)) 
                for d …