717. 1-bit and 2-bit Characters

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.

思路一：

class Solution {
public boolean isOneBitCharacter(int[] bits) {
int i = 0;
while(i < bits.length - 1)
{
if (bits[i] == 0) i++;
else i += 2;
}
return i == bits.length - 1;
}
}思路二：
只检查数列的最后一部分。

*如果最后两个数都为0，则true

*如果倒数第二个数为1，则取决于1的个数。1的个数为偶数，则true；1的个数为奇数，则false。

class Solution {
public boolean isOneBitCharacter(int[] bits) {
int i = bits.length - 2;
int ones = 0;
while (i >= 0 && bits[i] != 0)
{
ones++;
i--;
}
return ones % 2 == 0;
}
}思路三：
class Solution {
public boolean isOneBitCharacter(int[] bits) {
return bits.length <= 2 ? bits[0] == 0 : isOneBitCharacter(Arrays.copyOfRange(bits, bits[0] + 1, bits.length));
}
}