Day 3

CMakeLists.txt

@@ -12,3 +12,5 @@ add_executable(01A "solutions/01A.cpp")
 add_executable(01B "solutions/01B.cpp")
 add_executable(02A "solutions/02A.cpp")
 add_executable(02B "solutions/02B.cpp")
+add_executable(03A "solutions/03A.cpp")
+add_executable(03B "solutions/03B.cpp")

solutions/03A.cpp

@@ -0,0 +1,56 @@
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <vector>
+#include <bitset>
+
+constexpr std::size_t bSize = 12;
+
+const std::vector<std::string>& readToString(const std::string& path);
+const void getGammaEpsilon(std::bitset<bSize>& g, 
+                           std::bitset<bSize>& e, 
+                           const std::vector<std::string>& v);
+
+int main() 
+{
+
+  std::vector<std::string> inputs = readToString("../input/03.txt");
+  std::bitset<bSize> g, e;
+
+  getGammaEpsilon(g, e, inputs);
+
+  std::cout << (g.to_ulong() * e.to_ulong()) << std::endl;
+
+  return 0;
+}
+
+
+const std::vector<std::string>& readToString(const std::string& path)
+{
+  std::ifstream inputFile(path);
+  std::string input;
+  static std::vector<std::string> inputs;
+
+  while(std::getline(inputFile, input))
+    inputs.push_back(input);
+
+  inputFile.close();
+
+  return inputs;
+}
+
+const void getGammaEpsilon(std::bitset<bSize>& g, 
+                           std::bitset<bSize>& e, 
+                           const std::vector<std::string>& v)
+{
+  int bitOccurence [bSize]{};
+
+  for(const auto& el : v)
+    for(int b = 0; b < bSize; b++)
+      bitOccurence[b] += el[b] - 48;
+
+  for(int b = 0; b < bSize; b++)
+    g.set(bSize-b-1, bitOccurence[b] > v.size()/2);
+
+  e = ~g;  
+}

solutions/03B.cpp

@@ -0,0 +1,90 @@
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <vector>
+#include <bitset>
+#include <cmath>
+
+constexpr std::size_t bSize = 12;
+
+const std::vector<std::string>& readToString(const std::string& path);
+const void getGammaEpsilon(std::bitset<bSize>& g, 
+                           std::bitset<bSize>& e, 
+                           const std::vector<std::string>& v);
+const void filterCommonBit(int bit, const std::bitset<bSize>& f, std::vector<std::string>& v);
+std::string filterCommonBinary(bool common, std::vector<std::string> v);
+
+int main() 
+{
+  std::vector<std::string> inputs = readToString("../input/03.txt");
+  
+  std::bitset<bSize> o{filterCommonBinary(true, inputs)};
+  std::bitset<bSize> c{filterCommonBinary(false, inputs)};
+  
+  std::cout << o.to_ulong() * c.to_ulong() << std::endl;
+  
+  return 0;
+}
+
+const std::vector<std::string>& readToString(const std::string& path)
+{
+  std::ifstream inputFile(path);
+  std::string input;
+  static std::vector<std::string> inputs;
+
+  while(std::getline(inputFile, input))
+    inputs.push_back(input);
+
+  inputFile.close();
+
+  return inputs;
+}
+
+const void getGammaEpsilon(std::bitset<bSize>& g, 
+                           std::bitset<bSize>& e, 
+                           const std::vector<std::string>& v)
+{
+  int bitOccurence [bSize]{};
+
+  for(const auto& el : v)
+    for(int b = 0; b < bSize; b++)
+      bitOccurence[b] += el[b] - 48;
+
+  for(int b = 0; b < bSize; b++)
+    g.set(bSize-b-1, bitOccurence[b] >= round((float) v.size()/2));
+  
+
+  e = ~g;  
+}
+
+const void filterCommonBit(int bit, const std::bitset<bSize>& f, std::vector<std::string>& v)
+{
+  std::vector<std::string> nv;
+  
+
+  for(int i = 0; i < v.size(); i++) {
+    if(f[bSize-bit-1] == v[i][bit] - 48)
+      nv.push_back(v[i]);
+  }
+
+
+  v.clear();
+  for(const auto& e : nv)
+    v.push_back(e);
+}
+
+std::string filterCommonBinary(bool common, std::vector<std::string> v)
+{
+  std::bitset<bSize> g, e;
+
+  for(int b = 0; b < bSize; b++)
+  {
+    getGammaEpsilon(g, e, v);
+    filterCommonBit(b, common ? g : e, v);
+
+    if(v.size() == 1)
+      return v[0];
+  }
+
+  return "";
+}