From d58977fe0f11cabbd979167fd87f88c1748abc6a Mon Sep 17 00:00:00 2001
From: Clyne Sullivan <clyne@bitgloo.com>
Date: Sat, 17 Dec 2022 13:33:45 -0500
Subject: [PATCH] add day 17 part 1 c++

---
 day17/part1.cpp | 131 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 day17/part1.cpp

diff --git a/day17/part1.cpp b/day17/part1.cpp
new file mode 100644
index 0000000..f76787d
--- /dev/null
+++ b/day17/part1.cpp
@@ -0,0 +1,131 @@
+#include <array>
+#include <iostream>
+#include <string>
+#include <vector>
+
+static const std::array<unsigned int, 5> pieces = {
+    0x3C, 0x081C08, 0x10101C, 0x04040404, 0x0C0C
+};
+static auto next = pieces.begin();
+static auto current = *next;
+static unsigned int currenty;
+
+static void add(std::vector<unsigned char>& tet);
+static bool move(std::vector<unsigned char>& tet, char dir);
+static void show(const std::vector<unsigned char>& tet);
+
+int main()
+{
+    std::vector<unsigned char> tet;
+    std::string jet;
+
+    std::getline(std::cin, jet);
+
+    auto j = jet.cbegin();
+    for (int i = 0; i < 2022; ++i) {
+        add(tet);
+
+        while (move(tet, *j++)) {
+            if (tet.back() == 0)
+                tet.pop_back();
+
+            if (j >= jet.cend())
+                j = jet.cbegin();
+        }
+    }
+    std::cout << tet.size() << std::endl;
+
+    return 0;
+}
+
+void add(std::vector<unsigned char>& tet)
+{
+    tet.push_back(0);
+    tet.push_back(0);
+    tet.push_back(0);
+
+    current = *next;
+    currenty = tet.size();
+    for (auto n = current; n; n >>= 8)
+        tet.push_back(n);
+
+    if (++next >= pieces.end())
+        next = pieces.begin();
+}
+
+bool move(std::vector<unsigned char>& tet, char dir)
+{
+    auto tetcopy = tet;
+
+    if (dir == '<') {
+        if ((current & 0x0101) == 0) {
+            int i = currenty;
+            int shift = 1;
+            for (auto n = current; n; n >>= 8) {
+                auto t = tet[i] & ~n;
+                if (t & (n >> 1)) {
+                    shift = 0;
+                    tet = tetcopy;
+                    break;
+                }
+                tet[i] = t | n >> 1;
+                ++i;
+            }
+
+            if (shift)
+                current >>= 1;
+        }
+    } else if (dir == '>') {
+        if ((current & 0x4040) == 0) {
+            int i = currenty;
+            int shift = 1;
+            for (auto n = current; n; n >>= 8) {
+                auto t = tet[i] & ~n;
+                if (t & (n << 1)) {
+                    shift = 0;
+                    tet = tetcopy;
+                    break;
+                }
+                tet[i] = t | n << 1;
+                ++i;
+            }
+
+            if (shift)
+                current <<= 1;
+        }
+    } else {
+        return false;
+    }
+
+    if (currenty == 0)
+        return false;
+
+    tetcopy = tet;
+
+    int i = currenty;
+    for (auto n = current; n; n >>= 8) {
+        if (tet[i - 1] & n) {
+            tet = tetcopy;
+            return false;
+        }
+
+        tet[i] &= ~n;
+        tet[i - 1] |= n;
+        ++i;
+    }
+    --currenty;
+
+    return true;
+}
+
+void show(const std::vector<unsigned char>& tet)
+{
+    for (auto it = tet.rbegin(); it != tet.rend(); ++it) {
+        for (int i = 0; i < 7; ++i)
+            std::cout << ((*it & (1 << i)) ? '@' : '.');
+        std::cout << std::endl;
+    }
+
+    std::cout << std::endl;
+}
+