Add binomial_coefficient

snippets/binomial_coefficient.md

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+---
+title: binomial_coefficient
+tags: math,beginner
+---
+
+Return the number of ways to choose `k` items from `n` items without repetition and without order.
+
+- Use `math.comb()` to calculate the binomial coefficient.
+
+```py
+from math import comb
+
+def binomial_coefficient(n, k):
+  return comb(n, k)
+```
+
+```py
+binomial_coefficient(8, 2) # 28
+```