Rebased projecteuler folder, now includes all contest programming stuff

projecteuler/037/main.py

@@ -0,0 +1,53 @@
+'''
+The number 3797 has an interesting property. Being prime itself, it is possible to continuously remove digits from left to right, and remain prime at each stage: 3797, 797, 97, and 7. Similarly we can work from right to left: 3797, 379, 37, and 3.
+
+Find the sum of the only eleven primes that are both truncatable from left to right and right to left.
+
+Note: 2, 3, 5, and 7 are not considered to be truncatable primes.
+'''
+
+import math
+import numpy as np
+
+def sieve(n):
+    assert n > 1
+
+    ns = [True] * n
+
+    for i in range(2, math.ceil(np.sqrt(n))):
+        if ns[i]:
+            j = pow(i, 2)
+
+            while j < n:
+                ns[j] = False
+                j = j + i
+
+    return [i for i,val in enumerate(ns) if val][2:]
+
+def isTruncable(n, primes):
+    s = str(n)
+    for i in range(len(s)):
+        if int(s[:i+1]) not in primes or int(s[i:]) not in primes:
+            return False
+    
+    return True
+
+def main():
+    print("Hello this is Patrick")
+
+    primes = set(sieve(10000000))
+
+    truncs = []
+
+    i = 11
+    while len(truncs) < 11:
+        if isTruncable(i, primes):
+            truncs.append(i)
+            print(truncs)
+        i += 2
+
+    print(f"Trunc sum: {sum(truncs)}")
+
+
+if __name__ == "__main__":
+    main()