The count-and-say sequence is the sequence of integers beginning as follows:
1, 11, 21, 1211, 111221, ...
1
is read off as "one 1"
or 11
.11
is read off as "two 1s"
or 21
.21
is read off as "one 2
, then one 1"
or 1211
.
Given an integer n, generate the nth sequence.
Note: The sequence of integers will be represented as a string.
Solution:
class Solution: # @return a string def countAndSay(self, n): if n == 0 : return "" actual =['1'] for i in range(1,n): previous = actual actual = [] actChar = previous[0] count = 1 for j in range(1, len(previous)): if previous[j] == actChar: count += 1 else: actual.append(str(count)) actual.append(actChar) actChar = previous[j] count = 1 actual.append(str(count)) actual.append(actChar) return ''.join(actual)
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