Added year directories for advent of code

advent_of_code/2021/d8/main.cpp

@@ -0,0 +1,210 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+string file_name = "8.txt";
+// string file_name = "test_text.txt";
+
+vector<pair<array<string, 10>, array<string, 4>>> input_text;
+
+pair<array<string, 10>, array<string, 4>> parse_line(const string &s){
+    istringstream ss(s);
+    pair<array<string, 10>, array<string, 4>> result;
+    string word;
+
+    for(size_t i = 0; i < 10; ++i){
+        ss >> word;
+
+        result.first[i] = word;
+    }
+
+    // There should be a pipe | here, which doesn't need to be put into the strings
+    ss >> word;
+
+    for(size_t i = 0; i < 4; ++i){
+        ss >> word;
+
+        result.second[i] = word;
+    }
+
+    return result;
+}
+
+map<string, int> identify_digits(const array<string, 10> &digits){
+    map<int, string> digit_strings;
+
+    vector<string> size_fives;
+    vector<string> size_six;
+
+    for(size_t i = 0; i < 10; ++i){
+        size_t ds = digits[i].size();
+
+        if(ds == 2){
+            digit_strings[1] = digits[i];
+        } else if(ds == 3){
+            digit_strings[7] = digits[i];
+        } else if(ds == 4){
+            digit_strings[4] = digits[i];
+        } else if(ds == 7){
+            digit_strings[8] = digits[i];
+        } else if(ds == 5){
+            size_fives.push_back(digits[i]);
+        } else if(ds == 6){
+            size_six.push_back(digits[i]);
+        }
+    }
+
+    vector<set<char>> size_fives_sets(3);
+    for(int i = 0; i < 3; ++i){
+        for(char &c : size_fives[i]){
+            size_fives_sets[i].insert(c);
+        }
+
+        // We know that 2 is the only digit that combines with 4 to be 8
+        for(char &c : digit_strings[4]){
+            size_fives_sets[i].insert(c);
+        }
+
+        if(size_fives_sets[i].size() == 7){
+            digit_strings[2] = size_fives[i];
+            size_fives.erase(size_fives.begin() + i);
+            break;
+        }
+    }
+
+    // Now do kind of the same thing but for 5 and 3, combined with 7
+    set<char> three_or_five;
+    for(char &c : size_fives[0]){
+        three_or_five.insert(c);
+    }
+
+    for(char &c : digit_strings[7]){
+        three_or_five.insert(c);
+    }
+
+    // So in the case that it not of size 5, which means it is the number 5
+    if(three_or_five.size() != 5){
+        swap(size_fives[0], size_fives[1]);
+    }
+
+    digit_strings[3] = size_fives[0];
+    digit_strings[5] = size_fives[1];
+
+    vector<set<char>> size_six_sets(3);
+    for(int i = 0; i < 3; ++i){
+        for(char &c : size_six[i]){
+            size_six_sets[i].insert(c);
+        }
+
+        // Only 6 and 7 together form 8 from all the six sized digits
+        for(char &c : digit_strings[7]){
+            size_six_sets[i].insert(c);
+        }
+
+        if(size_six_sets[i].size() == 7){
+            digit_strings[6] = size_six[i];
+            size_six.erase(size_six.begin() + i);
+            break;
+        }
+    }
+
+    // Now we only need 9 and 0, which can be distinguished by combining with 4
+    set<char> nine_or_zero;
+    for(char &c : size_six[0]){
+        nine_or_zero.insert(c);
+    }
+
+    for(char &c : digit_strings[4]){
+        nine_or_zero.insert(c);
+    }
+
+    // In the case that the size is 7, which means it combines to an eight
+    if(nine_or_zero.size() != 7){
+        swap(size_six[0], size_six[1]);
+    }
+
+    digit_strings[0] = size_six[0];
+    digit_strings[9] = size_six[1];
+
+    for(auto &s : digit_strings){
+        sort(s.second.begin(), s.second.end());
+    }
+
+    map<string, int> result;
+    for(auto &d : digit_strings){
+        result[d.second] = d.first;
+    }
+
+    return result;
+}
+
+int main(){
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+
+    ifstream file_stream;
+    file_stream.open(file_name);
+
+    if(file_stream.is_open()){
+        string line;
+
+        while(getline(file_stream, line)){
+            input_text.push_back(parse_line(line));
+        }
+
+        file_stream.close();
+    }
+
+
+    // Testing the input parsing
+
+    // cout << input_text.size() << endl;
+    // for(const auto &line : input_text){
+    //     for(auto word : line.first){
+    //         cout << word << " ";
+    //     }
+
+    //     cout << "| ";
+
+    //     for(auto word : line.second){
+    //         cout << word << " ";
+    //     }
+
+    //     cout << endl;
+    // }
+
+    int result = 0;
+    for(const auto &line : input_text){
+        for(size_t i = 0; i < 4; ++i){
+            size_t w = line.second[i].size();
+            if(w == 2 || w == 4 || w == 3 || w == 7){
+                result++;
+            }
+        }
+    }
+
+    cout << result << endl;
+
+    result = 0;
+    for(auto &line : input_text){
+        auto digit_map = identify_digits(line.first);
+
+        int acc = 0;
+        for(int i = 0; i < 4; ++i){
+            string s = line.second[i];
+            sort(s.begin(), s.end());
+
+            acc *= 10;
+            acc += digit_map[s];
+        }
+
+        result += acc;
+    }
+
+    cout << result << endl;
+
+    cout << flush;
+
+    return 0;
+}