Fixing Typo (#244)

joaquingx · jakobkogler · commit 65aa1c028cd3 · 2018-04-06T19:33:31.000+02:00
diff --git a/src/string/prefix-function.md b/src/string/prefix-function.md
@@ -132,7 +132,7 @@ We generate the string $s + \\# + t$, where $\\#$ is a separator that appear in
 Let us calculate the prefix function for this string.
 Now think about the meaning of the values of the prefix function, except for the first $n + 1$ entries (which belong to the string $s$ and the separator).
 By definition the value $\pi[i]$ shows the longest length of a substring ending in position $i$ that coincides with the prefix.
-But in our case this is is nothing more than the largest block that coincides with $s$ and ends at position $i$.
+But in our case this is nothing more than the largest block that coincides with $s$ and ends at position $i$.
 This length cannot be bigger than $n$ due to the separator.
 But if equality $\pi[i] = n$ is achieved, then it means that the string $s$ appears completely in at this position, i.e. it ends at position $i$.
 Just do not forget that the positions are indexed in the string $s + \\# + t$.
