Update polynomial.md

peltorator · adamant-pwn · commit 77ef08ad68f4 · 2023-07-17T23:51:07.000+02:00
diff --git a/src/algebra/polynomial.md b/src/algebra/polynomial.md
@@ -384,7 +384,7 @@ The coefficient of $x^{n+r}$ of the product of the polynomials $A_0(x) = \sum\li
 Assume you need to calculate $A(x_1), \dots, A(x_n)$. As mentioned earlier, $A(x) \equiv A(x_i) \pmod{x-x_i}$. Thus you may do the following:
 
 1. Compute a segment tree such that in the segment $[l,r)$ stands the product $P_{l, r}(x) = (x-x_l)(x-x_{l+1})\dots(x-x_{r-1})$.
-2. Starting with $l=0$ and $r=n$ at the root node. Let $m=\lfloor(l+r)/2\rfloor$. Let's move down to $[l,m)$ with the polynomial $A(x) \pmod{P_{l,m}(x)}$.
+2. Starting with $l=1$ and $r=n+1$ at the root node. Let $m=\lfloor(l+r)/2\rfloor$. Let's move down to $[l,m)$ with the polynomial $A(x) \pmod{P_{l,m}(x)}$.
 3. This will recursively compute $A(x_l), \dots, A(x_{m-1})$, now do the same for $[m,r)$ with $A(x) \pmod{P_{m,r}(x)}$.
 4. Concatenate the results from the first and second recursive call and return them.
 
