Solve 2024 day 8 part 1

2024/day-08/day-08.pro

@@ -0,0 +1,7 @@
+TEMPLATE = app
+CONFIG += console c++20
+CONFIG -= app_bundle
+CONFIG -= qt
+
+SOURCES += \
+        main.cpp

2024/day-08/input

@@ -0,0 +1,50 @@
+........................E...j......W..........L...
+............................O........E.........L..
+..q......O...........l....................K.......
+............q...................HM......W.........
+................................1..H...........IW.
+....................5.............................
+..........k........M...wl............6............
+.....O.......w...k.....5.8..l......K.........o.6..
+.......k....w.........5.........R.....o........K..
+.....q..X..............j........E...I.........K...
+............O..........E........................H.
+................Mn.h2.w.p....................H....
+..................p.......a............j.....L....
+.....X...l.p.....................m.........W..6...
+..Xq................A..................R..m.......
+.........................i..........a..........R..
+...........u.....................a........I.....2.
+k..............A..n.........R.................o...
+................n.................Qo..............
+..........u.A.........h........2..................
+...5.......Y.....p...............iN...............
+1...x.....................i.......................
+........M..............2.....Qi...................
+...............................I..e...............
+......u......A...........m..........h.............
+.......1...........U.............Qm.......j.......
+.......X.......................................9..
+.....u........U.......Y...........................
+.............................h.e..................
+..................4....e......Q.....L....N........
+.1..................4.......................y8....
+.........Y................................8.N.....
+............P.0J...........3..........8y..........
+....V3P..........J................................
+............U..P...7x...........e.................
+....................J...............r...9.........
+.........0.V......Y...............................
+...............V.4................................
+..........V..........................n............
+..............v........7..........................
+...........U..........J.......7...................
+.....v........7..........................a........
+.......................................r..........
+...........0.......x................y.............
+............6..v.x.....................N..........
+...........P......................................
+........3.......................r......4..........
+..............3......................y............
+................................................9.
+.................................................9

2024/day-08/main.cpp

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+#include <iostream>
+#include <map>
+#include <set>
+#include <vector>
+
+using namespace std;
+
+void readInput(vector<string> &antennaMap, map<char, set<pair<int, int>>> &antennas)
+{
+    string line;
+    for (size_t row = 0; getline(cin, line); row++) {
+        for (size_t col = 0; col < line.size(); col++) {
+            char frequency = line[col];
+            if (frequency != '.') {
+                if (antennas.count(frequency)) {
+                    antennas.at(frequency).insert({row, col});
+                } else {
+                    antennas.insert({frequency, {{row, col}}});
+                }
+            }
+        }
+        antennaMap.push_back(line);
+    }
+}
+
+bool isInBounds(pair<int, int> location, const vector<string> &map)
+{
+    return (location.first >= 0 && location.first < map.size())
+           && (location.second >= 0 && location.second < map[0].size());
+}
+
+vector<pair<int, int>> getAntinodes(pair<int, int> antenna1,
+                                    pair<int, int> antenna2,
+                                    const vector<string> &antennaMap)
+{
+    if (antenna1 == antenna2) {
+        return {};
+    }
+
+    pair<int, int> directionVector = {antenna2.first - antenna1.first,
+                                      antenna2.second - antenna1.second};
+
+    pair<int, int> antinode1 = {antenna2.first + directionVector.first,
+                                antenna2.second + directionVector.second};
+    pair<int, int> antinode2 = {antenna1.first - directionVector.first,
+                                antenna1.second - directionVector.second};
+
+    vector<pair<int, int>> antinodes;
+    if (isInBounds(antinode1, antennaMap)) {
+        antinodes.push_back(antinode1);
+    }
+    if (isInBounds(antinode2, antennaMap)) {
+        antinodes.push_back(antinode2);
+    }
+    return antinodes;
+}
+
+int main()
+{
+    vector<string> antennaMap;
+    map<char, set<pair<int, int>>> antennas;
+    readInput(antennaMap, antennas);
+
+    set<pair<int, int>> uniqueAntinodes;
+
+    for (auto antennasWithSameFrequency : antennas) {
+        for (auto antenna1 : antennasWithSameFrequency.second) {
+            for (auto antenna2 : antennasWithSameFrequency.second) {
+                vector<pair<int, int>> foundAntinodes = getAntinodes(antenna1, antenna2, antennaMap);
+                for (pair<int, int> antinode : foundAntinodes) {
+                    uniqueAntinodes.insert(antinode);
+                }
+            }
+        }
+    }
+
+    // Part one
+    cout << "Number of unique antinodes: " << uniqueAntinodes.size() << endl;
+}

2024/day-08/short-input

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+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............