CS 271: Disjoint Set Naive Implementation (1.5 Points)

Developed by Professor Tralie and Professor Mongan.

---

Exercise Goals

The goals of this exercise are:

1. To use instance methods in python
2. To implement an ADT

Fill in the find method in the naive bubble list implementation of disjoint sets below.

Enter your Ursinus netid before clicking run. This is not your ID number or your email. For example, my netid is ctralie (non Ursinus students can simply enter their name to get this to run, but they won't get an e-mail record or any form of credit)

Netid

Clicking Run below will check your work and, if it passes, will submit your work automatically. If you are not on the campus network, you must be connected to the VPN for submission to be successful! You will receive a copy of your code via e-mail, so you'll know that it was submitted if you receive that e-mail! VPN access requires Multi-Factor Authentication, which sends you a code when you log into the network. Instructions on configuring these for your account can be found here.

Student Code

# List of lists, where each inner list corresponds to a bubble class DJSet: def __init__(self, N): self.N = N self.bubbles = [] for i in range(N): self.bubbles.append([i]) #self.bubbles = [[i] for i in range(N)] def _get_index_of(self, i): ret = -1 idx = 0 found = False while not found and idx < len(self.bubbles): bubble = self.bubbles[idx] for b in bubble: if i == b: ret = idx found = True idx += 1 return ret def union(self, i, j): """ Void method that unions two elements Parameters ---------- i: int First element to union j: int Second element to union """ # Figure out what bubble i is in idx_i = self._get_index_of(i) # Figure out what bubble j is in idx_j = self._get_index_of(j) if idx_i != idx_j: # Create a new bubble that merges the two bubble = self.bubbles[idx_i] + self.bubbles[idx_j] self.bubbles.append(bubble) # Delete the original two bubbles bubbles = [] for i in range(len(self.bubbles)): if i != idx_i and i != idx_j: bubbles.append(self.bubbles[i]) self.bubbles = bubbles def find(self, i, j): """ A method that says if two elements belong to the same set Parameters i: int First element j: int Second element Returns ------- True if i and j belong to the same set, and False otherwise """ pass

Test Code Block

# Run some tests on the class s = DJSet(10) s.union(0, 2) s.union(1, 8) s.union(8, 7) print(s.find(0, 3), end='.') print(s.find(1, 7), end='.') s.union(1, 6) s.union(0, 1) print(s.find(0, 7), end='.') print(s.find(1, 9))

Output

---