717. 1-bit and 2-bit Characters@python

Posted 2021-01-09 Chim

We have two special characters. The first character can be represented by one bit 0. The second character can be represented by two bits (10 or 11).

Now given a string represented by several bits. Return whether the last character must be a one-bit character or not. The given string will always end with a zero.

Example 1:

Input: 
bits = [1, 0, 0]
Output: True
Explanation: 
The only way to decode it is two-bit character and one-bit character. So the last character is one-bit character.

原题地址:  1-bit and 2-bit Characters

难度:  Easy

题意: 存在两类数,一类是10或者11,另一类为0.将一个数组拆分为这两类数,判断最后一组数为0,比如上面例子,第一组数为[1,0],第二组数为[0]

思路:

对于数字1,后面的一个数字是1或者0都行,所以遇到以可以跳过1后面的值,遇到0,则移动一位

代码:

class Solution(object):
    def isOneBitCharacter(self, bits):
        """
        :type bits: List[int]
        :rtype: bool
        """
        i = 0
        while i < len(bits):
            if bits[i] == 1:
                i += 2
                if i == len(bits):
                    return False
            else:
                i += 1
        return True

时间复杂度: O(n)

空间复杂度: O(1)