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 # ECE 250: DSA
 
+## Solving recurrences
+
+The **master method** is used to solve recurrences. For expressions of the form $T(n)=aT(n/b)+f(n)$:
+
+- If $f(n)=O(n^{\log_b a})$, we have $T(n)=\Theta(n^{\log_b a}\log n)$
+- If $f(n) < O(n^{\log_b a})$, we have $T(n)=O(n^{\log_b a})$
+- If $f(n) > \Omega(n^{\log_b a})$, and $af(n/b)\leq cf(n), c<0$, we have $T(n)=\Theta(f(n))$
+
+
 ## Heaps
 
 A heap is a binary tree **stored in an array** in which all levels but the lowest are filled. It is guaranteed that the parent of index $i$ is greater than or equal to the element at index $i$.