2016 2017 day6

4 files changed, 27 insertions, 14 deletions

diff --git a/src/2016/day6/aoc.cpp b/src/2016/day6/aoc.cpp
index 521ca55..02478fd 100644
--- a/src/2016/day6/aoc.cpp
+++ b/src/2016/day6/aoc.cpp
@@ -6,20 +6,26 @@ struct counter {
   int az[26] = {0};
 
   void add(char c) { az[c - 'a'] += 1; }
-  char most() {
+  std::pair<char, char> minmax() const noexcept {
     int max{INT32_MIN};
-    int index{0};
+    int min{INT32_MAX};
+    int i1{0};
+    int i2{0};
     for (int i = 0; i < 26; i++) {
-      if (az[i] > max) {
+      if (az[i] > 0 && az[i] > max) {
         max = az[i];
-        index = i;
+        i1 = i;
+      }
+      if (az[i] > 0 && az[i] < min) {
+        min = az[i];
+        i2 = i;
       }
     }
-    return 'a' + index;
+    return {'a' + i1, 'a' + i2};
   }
 };
 
-void day6(line_view file, char msg[]) {
+void day6(line_view file, char msg1[], char msg2[]) {
   counter cs[8];
   per_line(file, [&cs](line_view lv) {
     const char* p = lv.line;
@@ -34,7 +40,9 @@ void day6(line_view file, char msg[]) {
   });
 
   for (size_t i = 0; i < ARRAY_SIZE(cs); i++) {
-    msg[i] = cs[i].most();
+    auto p = cs[i].minmax();
+    msg1[i] = p.first;
+    msg2[i] = p.second;
   }
 }
 
diff --git a/src/2016/day6/aoc.h b/src/2016/day6/aoc.h
index 2ab2c4c..28bd318 100644
--- a/src/2016/day6/aoc.h
+++ b/src/2016/day6/aoc.h
@@ -3,5 +3,5 @@
 
 namespace aoc2016 {
 
-void day6(line_view, char[]);
+void day6(line_view, char[], char[]);
 }
diff --git a/src/2017/day6/aoc.cpp b/src/2017/day6/aoc.cpp
index 66511fd..c77e74f 100644
--- a/src/2017/day6/aoc.cpp
+++ b/src/2017/day6/aoc.cpp
@@ -3,7 +3,7 @@
 
 namespace aoc2017 {
 
-void next(int* step, memory_bank& m, std::set<memory_bank>& ms) {
+void next(int* step, int* gap, memory_bank& m, std::set<memory_bank>& ms) {
   if (ms.find(m) == ms.end()) {
     ms.insert(m);
     *step += 1;
@@ -11,16 +11,19 @@ void next(int* step, memory_bank& m, std::set<memory_bank>& ms) {
     int i = m.highest(&d);
     // printf("%d %d %d\n", *step, i, d);
     m.distribute(i, d);
-    next(step, m, ms);
+    next(step, gap, m, ms);
   }
+  auto it = ms.find(m);
+  *gap = *step - it->index;
 }
 
-int day6(line_view file) {
+std::pair<int, int> day6(line_view file) {
   std::set<memory_bank> ms;
   memory_bank m{file};
   int steps{0};
-  next(&steps, m, ms);
-  return steps;
+  int gap{0};
+  next(&steps, &gap, m, ms);
+  return {steps, gap};
 }
 
 } // namespace aoc2017
diff --git a/src/2017/day6/aoc.h b/src/2017/day6/aoc.h
index 8e8f043..328f382 100644
--- a/src/2017/day6/aoc.h
+++ b/src/2017/day6/aoc.h
@@ -5,6 +5,7 @@ namespace aoc2017 {
 
 struct memory_bank {
   int banks[16];
+  int index = 0;
 
   void get_number(const char** pp, int* d) {
     const char* p = *pp;
@@ -59,9 +60,10 @@ struct memory_bank {
       banks[i] += 1;
       x -= 1;
     }
+    index += 1;
   }
 };
 
-int day6(line_view);
+std::pair<int, int> day6(line_view);
 
 } // namespace aoc2017