CF639C.Bear and Polynomials
普及/提高-
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题目描述
Limak is a little polar bear. He doesn't have many toys and thus he often plays with polynomials.
He considers a polynomial valid if its degree is n and its coefficients are integers not exceeding k by the absolute value. More formally:
Let a0,a1,...,an denote the coefficients, so . Then, a polynomial P(x) is valid if all the following conditions are satisfied:
- ai is integer for every i ;
- ∣ai∣<=k for every i ;
- an=0 .
Limak has recently got a valid polynomial P with coefficients a0,a1,a2,...,an . He noticed that P(2)=0 and he wants to change it. He is going to change one coefficient to get a valid polynomial Q of degree n that Q(2)=0 . Count the number of ways to do so. You should count two ways as a distinct if coefficients of target polynoms differ.
输入格式
The first line contains two integers n and k ( 1<=n<=200000,1<=k<=109 ) — the degree of the polynomial and the limit for absolute values of coefficients.
The second line contains n+1 integers a0,a1,...,an ( ∣ai∣<=k,an=0 ) — describing a valid polynomial . It's guaranteed that P(2)=0 .
输出格式
Print the number of ways to change one coefficient to get a valid polynomial Q that Q(2)=0 .
输入输出样例
输入#1
3 1000000000 10 -9 -3 5
输出#1
3
输入#2
3 12 10 -9 -3 5
输出#2
2
输入#3
2 20 14 -7 19
输出#3
0
说明/提示
In the first sample, we are given a polynomial P(x)=10−9x−3x2+5x3 .
Limak can change one coefficient in three ways:
- He can set a0=−10 . Then he would get Q(x)=−10−9x−3x2+5x3 and indeed Q(2)=−10−18−12+40=0 .
- Or he can set a2=−8 . Then Q(x)=10−9x−8x2+5x3 and indeed Q(2)=10−18−32+40=0 .
- Or he can set a1=−19 . Then Q(x)=10−19x−3x2+5x3 and indeed Q(2)=10−38−12+40=0 .
In the second sample, we are given the same polynomial. This time though, k is equal to 12 instead of 109 . Two first of ways listed above are still valid but in the third way we would get |a_{1}|>k what is not allowed. Thus, the answer is 2 this time.