Added activity selection problem implementation and its tests

Author: OmkarPathak

pygorithm/greedy_algorithm/activity_selection.py

@@ -0,0 +1,44 @@
+"""
+Author: OMKAR PATHAK
+Created On: 26th August 2017
+"""
+
+import inspect
+
+def activity_selection(start_times, finish_times):
+    """
+    :param start_times: An array that contains start time of all activities
+    :param finish_times: An array that conatins finish time of all activities
+    """
+
+    if type(start_times) is not list:
+        raise TypeError("Activity selection problem only accepts lists, not {}".format(str(type(start_times))))
+
+    if type(finish_times) is not list:
+        raise TypeError("Activity selection problem only accepts lists, not {}".format(str(type(finish_times))))
+
+    if len(start_times) != len(finish_times):
+        raise ValueError('Length of start_times list and finish_times list must be same')
+
+    n = len(start_times)
+    activity = []
+
+    # first activity is also selected
+    i = 0
+    activity.append(i)
+
+    for j in range(n):
+        # If this activity has start time greater than
+        # or equal to the finish time of previously
+        # selected activity, then select it
+        if start_times[j] >= finish_times[i]:
+            activity.append(j)
+            i = j
+
+    return activity
+
+def get_code():
+    """
+    returns the code for the activity_selection function
+    """
+    return inspect.getsource(activity_selection)

tests/test_greedy_algorithm.py

@@ -3,6 +3,7 @@
 
 from pygorithm.greedy_algorithm import (
     fractional_knapsack,
+    activity_selection,
     )
 
 
@@ -13,5 +14,12 @@ def test_fractional_knapsack(self):
         W = 50
         self.assertEqual(fractional_knapsack.knapsack(W, value, weight), 240)
 
+class TestActivitySelectionProblem(unittest.TestCase):
+    def test_activity_selection(self):
+        start_times = [1 , 3 , 0 , 5 , 8 , 5]
+        finish_times = [2 , 4 , 6 , 7 , 9 , 9]
+
+        self.assertEqual(activity_selection.activity_selection(start_times, finish_times), [0, 1, 3, 4])
+
 if __name__ == '__main__':
     unittest.main()