day 20 part 1

2 files changed, 63 insertions, 0 deletions

diff --git a/22.20/main.cpp b/22.20/main.cpp
new file mode 100644
index 0000000..753cdf5
--- /dev/null
+++ b/22.20/main.cpp
@@ -0,0 +1,47 @@
+/* The reason I gave up on this:
+ * I thought I'd need to somehow track the first "node", so I wanted to
+ * experiment on a more naive implementation. I don't.
+ * Also, the dumb algorithm is still by far fast enough. So, Python it is. */
+#include <cstdio>
+#include <vector>
+using namespace std;
+
+struct CNode
+{
+	size_t id;
+	CNode *prev = NULL, *next = NULL;
+};
+
+struct Circular
+{
+	vector<CNode> nodes;
+	Circular(size_t size) {
+		for (size_t i = 0; i < size; i++) {
+			nodes.push_back(CNode{i});
+		}
+
+		// pointers to stuff in a vector? how risque!
+		for (size_t i = 0; i < size - 1; i++) {
+			nodes[i].next = &nodes[i+1];
+			nodes[i+1].prev = &nodes[i];
+		}
+		CNode *f = &nodes.front();
+		CNode *b = &nodes.back();
+		f->prev = b;
+		b->next = f;
+	}
+
+	void print() {
+	}
+};
+
+int
+main()
+{
+	int n;
+	vector<int> input;
+	while (scanf("%d ", &n) == 1) {
+		input.push_back(n);
+	}
+	Circular c(input.size());
+}
diff --git a/22.20/main.py b/22.20/main.py
new file mode 100644
index 0000000..7cb46de
--- /dev/null
+++ b/22.20/main.py
@@ -0,0 +1,16 @@
+from sys import stdin
+a = [int(n) for n in stdin.readlines()]
+
+p = list(range(len(a)))
+
+for i, n in enumerate(a):
+    og_idx = p.index(i)
+    p.pop(og_idx)
+    og_idx = (og_idx + n) % len(p)
+    if og_idx == 0 and n < 0: og_idx = len(p)
+    p.insert(og_idx, i)
+
+a = [a[i] for i in p]
+def g(n): return a[(a.index(0) + n) % len(a)]
+
+print(g(1000) + g(2000) + g(3000))