of using -> by using

Oleksandr Kulkov · adamant-pwn · commit 7df7fccf3cfb · 2023-01-06T23:15:34.000+01:00
diff --git a/src/data_structures/segment_tree.md b/src/data_structures/segment_tree.md
@@ -159,7 +159,7 @@ The green vertices are the vertices that we visit and update.
 The main consideration is how to store the Segment Tree.
 Of course we can define a $\text{Vertex}$ struct and create objects, that store the boundaries of the segment, its sum and additionally also pointers to its child vertices.
 However, this requires storing a lot of redundant information in the form of pointers.
-We will use a simple trick to make this a lot more efficient of using an _implicit data structure_: Only storing the sums in an array.
+We will use a simple trick to make this a lot more efficient by using an _implicit data structure_: Only storing the sums in an array.
 (A similar method is used for binary heaps).
 The sum of the root vertex at index 1, the sums of its two child vertices at indices 2 and 3, the sums of the children of those two vertices at indices 4 to 7, and so on. 
 With 1-indexing, conveniently the left child of a vertex at index $i$ is stored at index $2i$, and the right one at index $2i + 1$. 
