Solve problem 109 in Python

python/e109.py

@@ -0,0 +1,73 @@
+
+def all_singles():
+    return list(range(1, 21)) + [25]
+
+
+def all_doubles():
+    return [n * 2 for n in range(1, 21)] + [50]
+
+
+def all_triples():
+    return [n * 3 for n in range(1, 21)]
+
+
+def euler_109():
+    count = 0
+    target_score = 100
+    for first in all_doubles():
+        # D
+        if first < target_score:
+            count += 1
+
+        # D T
+        for second in all_triples():
+            if first + second < target_score:
+                count += 1
+        # D D
+        for second in all_doubles():
+            if first + second < target_score:
+                count += 1
+        # D S
+        for second in all_singles():
+            if first + second < target_score:
+                count += 1
+
+        # D T D
+        for second in all_triples():
+            for third in all_doubles():
+                if first + second + third < target_score:
+                    count += 1
+        # D T S
+        for second in all_triples():
+            for third in all_singles():
+                if first + second + third < target_score:
+                    count += 1
+        # D D S
+        for second in all_doubles():
+            for third in all_singles():
+                if first + second + third < target_score:
+                    count += 1
+
+        # D T T
+        for second in all_triples():
+            for third in all_triples():
+                if second >= third and first + second + third < target_score:
+                    count += 1
+
+        # D D
+        for second in all_doubles():
+            for third in all_doubles():
+                if second >= third and first + second + third < target_score:
+                    count += 1
+        # S S
+        for second in all_singles():
+            for third in all_singles():
+                if second >= third and first + second + third < target_score:
+                    count += 1
+    return count
+
+
+if __name__ == "__main__":
+    solution = euler_109()
+    print("e109.py: " + str(solution))
+    assert(solution == 38182)