Found the longest Collatz chain: 837799

14/main.py

@@ -0,0 +1,64 @@
+import os
+import math
+import numpy as np
+
+
+# Given the following sequence, find the longest chain that ends with 1 and starts with some number under a million
+
+# n -> n/2    | n is even
+# n -> 3n + 1 | n is odd
+
+def next(n):
+    if n % 2 == 0:
+        return int(n/2)
+    else:
+        return (3*n + 1)
+
+def sequence(n):
+    res = [n]
+
+    while res[-1] != 1:
+        res.append(next(res[-1]))
+
+    return res
+
+
+def getLongestSequence(n):
+    seqLengths = [0] * n
+    seqLengths[0] = 1
+
+    for x in range(1, n):
+        i = x + 1
+        l = 1
+
+        while True:
+            if i == 1:
+                break
+            elif i < n + 1 and seqLengths[i - 1] > 0:
+                l = l + seqLengths[i - 1] - 1
+                break
+            else:
+                l = l + 1
+                i = next(i)
+
+        seqLengths[x] = l
+        print(x + 1, l)
+
+    return seqLengths
+
+
+def main():
+    print("Hello, this is Patrick")
+
+    t = getLongestSequence(1000000)
+
+    m = t[0]
+    j = 0
+    for i in range(len(t)):
+        if t[i] > m:
+            m = t[i]
+            j = i
+    print("Max", j + 1, m)
+
+if __name__ == "__main__":
+    main()