added ws202425 courses

2023_CS50X/python/world-cup/answers.txt

@@ -0,0 +1,19 @@
+Times:
+
+10 simulations: 0m0.021s
+100 simulations: 0m0.027s
+1000 simulations: 0m0.040s
+10000 simulations: 0m0.084s
+100000 simulations: 0m0.728s
+1000000 simulations: 0m6.556s
+
+Questions:
+
+Which predictions, if any, proved incorrect as you increased the number of simulations?:
+
+With a small number of simulations.
+
+Suppose you're charged a fee for each second of compute time your program uses.
+After how many simulations would you call the predictions "good enough"?: TODO
+
+Predictions stabilized over 10000 simulations.

2023_CS50X/python/world-cup/tournament.py

@@ -0,0 +1,69 @@
+# Simulate a sports tournament
+
+import csv
+import sys
+import random
+
+# Number of simluations to run
+N = 1000
+
+
+def main():
+
+    # Ensure correct usage
+    if len(sys.argv) != 2:
+        sys.exit("Usage: python tournament.py FILENAME")
+
+    teams = []
+    counts = {}
+
+    # TODO: Read teams into memory from file
+    with open(sys.argv[1], 'r') as csvfile:
+        reader = csv.DictReader(csvfile)
+        for row in reader:
+            teams.append({'team': row['team'], 'rating': int(row['rating'])})
+            counts[row['team']] = 0
+
+    # TODO: Simulate N tournaments and keep track of win counts
+    for _ in range(N):
+        winner = simulate_tournament(teams.copy())
+        counts[winner] += 1
+
+    # Print each team's chances of winning, according to simulation
+    for team in sorted(counts, key=lambda team: counts[team], reverse=True):
+        print(f"{team}: {counts[team] * 100 / N:.1f}% chance of winning")
+
+
+def simulate_game(team1, team2):
+    """Simulate a game. Return True if team1 wins, False otherwise."""
+    rating1 = team1["rating"]
+    rating2 = team2["rating"]
+    probability = 1 / (1 + 10 ** ((rating2 - rating1) / 600))
+    return random.random() < probability
+
+
+def simulate_round(teams):
+    """Simulate a round. Return a list of winning teams."""
+    winners = []
+
+    # Simulate games for all pairs of teams
+    for i in range(0, len(teams), 2):
+        if simulate_game(teams[i], teams[i + 1]):
+            winners.append(teams[i])
+        else:
+            winners.append(teams[i + 1])
+
+    return winners
+
+
+def simulate_tournament(teams):
+    """Simulate a tournament. Return name of winning team."""
+    # TODO
+
+    while len(teams) > 1:
+        teams = simulate_round(teams)
+    return teams[0]['team']
+
+
+if __name__ == "__main__":
+    main()