Solve 204.

python/e204.py

@@ -0,0 +1,38 @@
+from lib_prime import primes
+from functools import lru_cache
+
+
+@lru_cache
+def next_prime(n):
+    if n == 1:
+        return 2
+    ps = primes(105)
+    assert n < ps[-1]
+    for i, p in enumerate(ps):
+        if p == n and i + 1 < len(ps):
+            return ps[i + 1]
+    assert False
+
+
+def count(current_product, max_product, current_prime, max_prime):
+    if current_product > max_product:
+        return 0
+    r = 1
+
+    if current_prime > 1:
+        r += count(current_product * current_prime, max_product, current_prime, max_prime)
+
+    while (current_prime := next_prime(current_prime)) <= max_prime:
+        r += count(current_product * current_prime, max_product, current_prime, max_prime)
+    return r
+
+
+def euler_204():
+    assert count(1, 10**8, 1, 5) == 1105
+    return count(1, 10**9, 1, 100)
+
+
+if __name__ == "__main__":
+    solution = euler_204()
+    print("e204.py: " + str(solution))
+    assert(solution == 2944730)