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.

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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))