Cs50 Tideman - Solution

The recursive function must traverse the graph to see if the new edge completes a cycle.

: Candidates are nodes, and preferred matchups are directed edges (arrows pointing from winner to loser).

// Function to read input void read_input(int *voters, int *candidates, voter_t **voters_prefs) // Read in the number of voters and candidates scanf("%d %d", voters, candidates);

If you find a path that leads back to your original winner, a cycle exists.

The algorithm determines a winner through three main principles: : Voters rank all candidates (e.g., Cs50 Tideman Solution

The CS50 Tideman problem is a popular problem set from the Harvard University's CS50 introductory computer science course. In this problem, students are tasked with implementing a voting system called Tideman, named after the American mathematician and computer scientist Ralph Tideman. The goal of the problem is to create a program that can accurately determine the winner of an election using the Tideman voting system.

# Determine the winner pair_wins = [0 for _ in range(num_candidates)] for i in range(num_candidates): for j in range(num_candidates): if i != j and vote_count[i][j] > vote_count[j][i]: pair_wins[i] += 1

Thus, your cycle check must be:

Use make tideman and ./tideman [candidates] to test each function individually. The recursive function must traverse the graph to

To successfully write the solution, you must complete six specific functions inside the provided CS50 distribution code. 1. vote

: The winner is the "source" of the graph—the candidate with no arrows pointing at them. Core Data Structures

Test your cycle detection on this example:

if (from == target) return true; for (int i = 0; i < candidate_count; i++) The algorithm determines a winner through three main

Use qsort() with a custom comparator that compares margins.

The Tideman solution forces you to think algorithmically about graph theory, recursion, and sorting. It’s not about getting the code right on the first try, but about breaking the problem into small, testable pieces.

The core unit of the Tideman algorithm is the pairwise comparison. A pair struct is defined to hold the indices of the winner and loser of a specific matchup:

(the margin by which the winner defeated the loser). Sorting ensures that the most significant mandates are "locked" into the graph first. 3. Lock Pairs and Avoid Cycles This is the core and most difficult part of the algorithm. lock_pairs