Small fixes

luku08.tex

@@ -245,13 +245,13 @@ Since both the left and right pointer
 move $O(n)$ steps during the algorithm,
 the time complexity is $O(n)$.
 
-\subsubsection{2SUM-problem}
+\subsubsection{2SUM problem}
 
-\index{2SUM-problem}
+\index{2SUM problem}
 
 Another problem that can be solved using
 the two pointers method is the following problem,
-also known as the \key{2SUM-problem}:
+also known as the \key{2SUM problem}:
 We are given an array of $n$ numbers and
 a target sum $x$, and our task is to find two numbers
 in the array such that their sum is $x$,
@@ -414,13 +414,13 @@ number such that the sum is $x$.
 This can be done by performing $n$ binary searches,
 and each search takes $O(\log n)$ time.
 
-\index{3SUM-problem}
+\index{3SUM problem}
 A more difficult problem is 
-the \key{3SUM-problem} that asks to
+the \key{3SUM problem} that asks to
 find \emph{three} numbers in the array
 such that their sum is $x$.
 This problem can be solved in $O(n^2)$ time.
-Can you see how it is possible?
+Can you see how?
 
 \section{Nearest smaller elements}