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.
解法一(普通):
bool isOneBitCharacter(vector<int>& bits) {
int n = bits.size();
if(n == 1) return true;
if(bits[n-2] == 0) return true;
if(n == 2 || (n>=3 && bits[n-3] == 0))
return false;
//how many '1' continuous
int i = n-2;
while(i>=0 && bits[i] == 1)
i--;
if((n-2-i) % 2 == 0) return true;
else return false;
}
解法二(高端):
bool isOneBitCharacter(vector<int>& bits) {
int i = 0, n = bits.size();
while(i < n-1){
if(bits[i] == 0) i++;
else i += 2;
}
return i == n-1;
}
看到0后移一个,看到1后移两个。
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