Lock B→C. Graph: A→B→C.
if (locked[j][i]) // j beats i
Identify the candidate with no arrows pointing to them (the source of the graph).
function, you receive a voter's rank (0 for 1st choice, 1 for 2nd, etc.) and a candidate's name. : Loop through the candidates array. If the name matches, update the array at the specified rank with the candidate's index. : Create a ranked list for each voter (e.g., ranks[0] = 2 means candidate 2 is this voter's first choice). Dev Genius 2. Populate Preferences Matrix record_preferences function updates the global preferences[i][j] 2D array, which stores how many voters prefer candidate over candidate Dev Genius Cs50 Tideman Solution
The strength of victory is defined by preferences[pair.winner][pair.loser] .
If locking a pair would create a cycle, you must it. This ensures that the final graph is acyclic, guaranteeing a clear source (winner).
In a Tideman election:
The key insight is to use a nested loop. For each candidate i in the voter's ranking, you need to consider all candidates j that they prefer less. The preferences count is increased for every preferred candidate ( ranks[i] ) over every less-preferred candidate ( ranks[j] ).
Update the global preferences[i][j] array. preferences[i][j] stores the number of voters who prefer candidate i over candidate j.
: After all non-cyclical pairs are locked, the program scans the The "Source" : The winner is the candidate who is the Lock B→C
bool vote(int rank, string name, int ranks[]) for (int i = 0; i < candidate_count; i++) if (strcmp(candidates[i], name) == 0) ranks[rank] = i; return true; return false; Use code with caution. 2. record_preferences
Sort the pairs in decreasing order of victory strength (margin of victory). Using bubble sort or selection sort is sufficient.
Why loser → winner in the check? Because we already have edges in direction of winner → loser. If loser can reach winner , adding winner → loser closes the cycle. function, you receive a voter's rank (0 for
void print_winner(void)