Readable code, function docstring and doctests

greedy_methods/fractional_knapsack.py

@@ -1,24 +1,42 @@
 from bisect import bisect
 from itertools import accumulate
 
+# Reference Link: https://en.wikipedia.org/wiki/Continuous_knapsack_problem
 
-def frac_knapsack(vl, wt, w, n):
+
+def frac_knapsack(vl: list, wt: list, w: int, n: int) -> float:
     """
+    This function implements fractional knapsack problem.
+
+    Args:
+        vl: List of values of items.
+        wt: List of weights of items.
+        w: Capacity of the knapsack.
+        n: Number of items.
+
+    Returns:
+        Maximum value of items that can be put into the knapsack.
+
     >>> frac_knapsack([60, 100, 120], [10, 20, 30], 50, 3)
     240.0
+    >>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 10, 4)
+    105.0
+    >>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 8, 4)
+    95.0
     """
 
+    # sort in descending order of value/weight ratio
     r = sorted(zip(vl, wt), key=lambda x: x[0] / x[1], reverse=True)
-    vl, wt = [i[0] for i in r], [i[1] for i in r]
-    acc = list(accumulate(wt))
-    k = bisect(acc, w)
-    return (
-        0
-        if k == 0
-        else sum(vl[:k]) + (w - acc[k - 1]) * (vl[k]) / (wt[k])
-        if k != n
-        else sum(vl[:k])
-    )
+
+    vl, wt = [i[0] for i in r], [i[1] for i in r]  # unzip the list
+    acc = list(accumulate(wt))  # cumulative sum of weights
+    k = bisect(acc, w)  # find the index of the weight just greater than w
+
+    if k == 0:  # no item can be put into the knapsack
+        return 0
+    elif k != n:  # fractional part of the kth item can be put into the knapsack
+        return sum(vl[:k]) + (w - acc[k - 1]) * (vl[k]) / (wt[k])
+    return sum(vl[:k])  # all items can be put into the knapsack
 
 
 if __name__ == "__main__":