Add kattis prob walrusweights in python2 + notes

kattis/walrusweights/notes.md

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+Iterate through the numbers, summing each one and every other number you have ever seen before (a set called `seen`), and making this your new `seen` set. However, this will run out of time. But you can throw away any numbers that are obviously too large and will not get you any closer to your goal of `1000`. This solution runs in 0.05s in python2, and 0.25s in python3.

kattis/walrusweights/solution.py

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+def main():
+    n = int(raw_input())
+    m = sorted(map(int, (raw_input() for _ in range(n))))
+    seen = set()
+    seen.add(0)
+    best = 0
+    bestdiff = 1000
+    for i in m:
+        for o in list(seen):
+            d = abs(1000 - (i+o))
+            if d == bestdiff and best < (i+o):
+                best = (i+o)
+            elif d < bestdiff:
+                best = (i+o)
+                bestdiff = d
+            if d > bestdiff and (i+o) > 1000:
+                continue
+            seen.add(i+o)
+    print(best)
+
+main()