717. 1-bit and 2-bit Characters

本文出处

题目描述:

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.

Example 2: Input: bits = [1, 1, 1, 0] Output: False Explanation: The

only way to decode it is two-bit character and two-bit character. So

the last character is NOT one-bit character.

Note:

1 <= len(bits) <= 1000. bits[i] is always 0 or 1.

根据题目大意，给定一01串，判断该串的最后一个字符是否是one-bit。从给定串的开始部分开始扫描，根据条件，判断该bit是one-bit or two-bit，取决于该位是不是1。因此，我们能很容易的根据一个字符的首位（如果是1，则为two-bit; 如果是0，则为one-bit）。所以扫描该串即可轻松解决。

Solution:

class Solution {
public:
bool isOneBitCharacter(vector<int>& bits) {
bool ret = false;
for (int i = 0; i < bits.size(); ++i) {
if (bits[i] == 1) {
ret = false;
i++;
} else {
ret = true;
}
}
return ret;

}
};

复杂度：

时间复杂度：O(n)