6

Author: gogsbread

cpp/6.cpp

@@ -0,0 +1,27 @@
+#include "common.h"
+
+namespace {
+long p(const auto &input, size_t m) {
+  const auto &s = input[0];
+  std::unordered_map<char, long> st;
+  for (size_t i = 0; i < m - 1; ++i)
+    st[s[i]] += 1;
+
+  for (size_t i = m - 1; i < s.size(); ++i) {
+    st[s[i]] += 1;
+    if (st.size() == m)
+      return i + 1;
+    st[s[i - m + 1]] -= 1;
+    if (!st.at(s[i - m + 1])) {
+      st.erase(s[i - m + 1]);
+    }
+  }
+  return -1;
+}
+} // namespace
+
+int main() {
+  const auto &input = gb::advent2021::readIn();
+  gb::advent2021::writeOut(std::to_string(p(input, 4)));
+  gb::advent2021::writeOut(std::to_string(p(input, 14)));
+}

cpp/meson.build

@@ -22,9 +22,9 @@ executable('5',
     '5.cpp',
     dependencies: [])
 
-# executable('6',
-#     '6.cpp',
-#     dependencies: [])
+executable('6',
+    '6.cpp',
+    dependencies: [])
 
 # executable('7',
 #     '7.cpp',