Add weighted simple random sampling function

Week02/weighted_buse_cici.py

@@ -0,0 +1,8 @@
+import random
+def weighted_srs(data, n, weights, with_replacement = False):
+    if with_replacement :
+        return random.choices(data, weights = weights, k = n)
+    if weights is None :
+        return random.sample(data, n)
+    else :
+        return random.sample(data, n, counts = weights)