在Python中实现运行长度字符串解码迭代器类的程序
假设我们想定义一个迭代器类，它用一个运行长度编码的小写字符串比如s来构造，这个迭代器有两个函数，它们是-
next()this找到迭代器中的下一个元素
hasnext()这会检查下一个元素是否存在
所以，如果输入像s="2b1a"，那么用s构造一个对象，然后调用next(),hasnext(),next(),next(),hasnext(),那么输出将是"b",True,"b","a",False。
示例
让我们看看以下实现以获得更好的理解-
class RunLengthIterator:
def __init__(self, s):
self.output = []
num = ""
for i in s:
if i.isalpha():
self.output.append(int(num))
self.output.append(i)
num = ""
else:
num += i
def next(self):
if self.hasnext():
count = self.output[0]
letter = self.output[1]
count -= 1
if count > 0:
self.output[0] -= 1
else:
self.output= self.output[2:]
return letter
def hasnext(self):
if len(self.output) != 0:
return True
return False
s = "2b1a"
obj = RunLengthIterator(s)
print(obj.next())
print(obj.hasnext())
print(obj.next())
print(obj.next())
print(obj.hasnext())输入
"2b1a" obj = RunLengthIterator(s) obj.next() obj.hasnext() obj.next() obj.next() obj.hasnext()输出结果
b True b a False