diff --git a/day 10/day_10_felix.cpp b/day 10/day_10_felix.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7f04f50535a153714458168d97ce1fdc9c527ed9
--- /dev/null
+++ b/day 10/day_10_felix.cpp
@@ -0,0 +1,114 @@
+#include <bits/stdc++.h>
+using namespace std;
+const bool DEBUG = false;
+
+#define coord pair<int, int>
+
+vector<vector<int>> trailMap;
+vector<coord> trailHeads;
+coord mapSize;
+const vector<coord> DIRS = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
+
+void parseMap() {
+ DEBUG && cout << "Parsing map" << endl;
+ string line;
+ stringstream ss;
+ char c;
+ int row = 0;
+ int col = 0;
+ while (getline(cin, line)) {
+ DEBUG && cout << "Read line: " << line << endl;
+ ss = stringstream(line);
+ col = 0;
+ while (ss >> c) {
+ if (c == '0') trailHeads.push_back({row, col});
+ if (col == 0) trailMap.push_back({c - '0'});
+ else trailMap[row].push_back(c - '0');
+ col++;
+ }
+ row++;
+ }
+ mapSize = {row, col};
+}
+
+bool printMap() {
+ for (int i = 0; i < mapSize.first; i++) {
+ for (int j = 0; j < mapSize.second; j++) {
+ cout << trailMap[i][j] << " ";
+ }
+ cout << endl;
+ }
+ return false;
+}
+
+bool isInBounds(coord c) {
+ return c.first >= 0 && c.first < mapSize.first && c.second >= 0 && c.second < mapSize.second;
+}
+
+bool islegall(coord curr, coord next) {
+ return isInBounds(next) && trailMap[next.first][next.second] == trailMap[curr.first][curr.second] + 1;
+}
+
+int searchPart1(coord head) {
+ DEBUG && cout << "Searching from " << head.first << " " << head.second << endl;
+ vector<coord> toSearch = {head};
+ int n_nines = 0;
+ array<array<bool, 100>, 100> visited = {false};
+ while (!toSearch.empty()) {
+ coord curr = toSearch.back();
+ toSearch.pop_back();
+ if (visited[curr.first][curr.second]) continue;
+ visited[curr.first][curr.second] = true;
+ if (trailMap[curr.first][curr.second] == 9) {
+ n_nines++;
+ DEBUG && cout << " Found a 9 at " << curr.first << " " << curr.second << endl;
+ continue;
+ }
+ for (coord dir : DIRS) {
+ coord next = {curr.first + dir.first, curr.second + dir.second};
+ if (islegall(curr,next)) toSearch.push_back(next);
+ }
+ }
+ return n_nines;
+}
+
+int searchPart2(coord head) {
+ DEBUG && cout << "Searching from " << head.first << " " << head.second << endl;
+ vector<coord> toSearch = {head};
+ int n_nines = 0;
+ //array<array<bool, 100>, 100> visited = {false};
+ while (!toSearch.empty()) {
+ coord curr = toSearch.back();
+ toSearch.pop_back();
+ //if (visited[curr.first][curr.second]) continue;
+ //visited[curr.first][curr.second] = true;
+ if (trailMap[curr.first][curr.second] == 9) {
+ n_nines++;
+ DEBUG && cout << " Found a 9 at " << curr.first << " " << curr.second << endl;
+ continue;
+ }
+ for (coord dir : DIRS) {
+ coord next = {curr.first + dir.first, curr.second + dir.second};
+ if (islegall(curr,next)) toSearch.push_back(next);
+ }
+ }
+ return n_nines;
+}
+
+
+
+
+
+int main () {
+ parseMap();
+ DEBUG && printMap();
+ int p1 = 0;
+ int p2 = 0;
+ for (coord head : trailHeads) {
+ p1 += searchPart1(head);
+ p2 += searchPart2(head);
+ }
+ cout << "Part 1: " << p1 << endl;
+ cout << "Part 2: " << p2 << endl;
+ return 0;
+}
\ No newline at end of file
diff --git a/day 11/day_11_felix.cpp b/day 11/day_11_felix.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5426f72b6e0cb46d77e4124f837ff2d099517fba
--- /dev/null
+++ b/day 11/day_11_felix.cpp
@@ -0,0 +1,71 @@
+#include <bits/stdc++.h>
+using namespace std;
+const bool DEBUG = true;
+
+#define ll long long
+
+void add_to_map(map<ll, ll> &x, ll key, ll value) {
+ if (x.find(key) == x.end()) {
+ x[key] = value;
+ } else {
+ x[key] += value;
+ }
+}
+
+map<ll,ll> step(const map<ll,ll> &x0) {
+ map<ll, ll> x1;
+ for (auto [stone, count] : x0) {
+ if (count == 0) continue;
+ string numstring = to_string(stone);
+ if (stone == 0) add_to_map(x1, 1, count);
+ else if (numstring.size() % 2 == 0) {
+ ll left = stoi(numstring.substr(0, numstring.size() / 2));
+ ll right = stoi(numstring.substr(numstring.size() / 2, numstring.size() / 2));
+ add_to_map(x1, left, count);
+ add_to_map(x1, right, count);
+ } else {
+ if (stone >= LLONG_MAX / 2024) cout << "TOO LARGE! " << stone << endl;
+ add_to_map(x1, stone * 2024, count);
+ }
+ }
+ return x1;
+}
+
+map<ll,ll> read_input() {
+ map<ll, ll> state;
+ ll stone;
+ DEBUG && cout << "Reading input" << endl;
+ while (cin >> stone) {
+ DEBUG && cout << " Stone: " << stone << endl;
+ add_to_map(state, stone, 1);
+ }
+ DEBUG && cout << "Input read" << endl;
+ return state;
+}
+
+ll sum_over(map<ll,ll> x) {
+ ll sum = 0;
+ for (auto [stone, count] : x) {
+ sum += count;
+ }
+ return sum;
+}
+
+int main () {
+ map<ll,ll> state = read_input();
+
+ for (int i = 0; i < 25; i++) {
+ state = step(state);
+ }
+ cout << "Part 1: " << sum_over(state) << endl;
+ for (int i = 0; i < 50; i++) {
+ state = step(state);
+ DEBUG && cout << "Step: " << i+25 << endl;
+ for (auto [stone, count] : state) {
+ DEBUG && cout << " Stone: " << stone << " Count: " << count << endl;
+ }
+ }
+ cout << "Part 2: " << sum_over(state) << endl;
+
+ return 0;
+}
\ No newline at end of file
diff --git a/day 8/day_8_felix.cpp b/day 8/day_8_felix.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..4913e71f52f4e0989f51e14ea6c54d9f71c496a0
--- /dev/null
+++ b/day 8/day_8_felix.cpp
@@ -0,0 +1,159 @@
+#include <bits/stdc++.h>
+using namespace std;
+const bool DEBUG = true;
+
+#define coord pair<int, int>
+map <char, vector<coord>> beacons;
+int nrows = 0;
+int ncols = 0;
+
+void parseInput() {
+ string line;
+ int row = 0;
+ while (getline(cin, line)) {
+ nrows++;
+ ncols = line.size();
+ for (int col = 0 ; col < line.size(); col++) {
+ if (line[col] != '.') {
+ beacons[line[col]].push_back({row, col});
+ }
+ }
+ row++;
+ }
+}
+
+bool isInBounds(coord a) {
+ return a.first >= 0 && a.first < nrows && a.second >= 0 && a.second < ncols;
+}
+
+pair<coord, coord> antinodePositions(coord a, coord b) {
+ coord newA = {a.first - (b.first - a.first), a.second - (b.second - a.second)};
+ coord newB = {b.first + (b.first - a.first), b.second + (b.second - a.second)};
+ return {newA, newB};
+}
+
+vector<coord> resonanceNodes(coord a, coord b) {
+ vector<coord> resNodes;
+ int dx = b.first - a.first;
+ int dy = b.second - a.second;
+ // Check modulus?
+ while (dx % 3 == 0 && dy % 3 == 0) {
+ dx = dx/3;
+ dy = dy/3;
+ cout << "Found modulus 3!" << endl;
+ }
+ while (dx % 2 == 0 && dy % 2 == 0) {
+ dx = dx/2;
+ dy = dy/2;
+ cout << "Found modulus 2!" << endl;
+ }
+ while (dx % 5 == 0 && dy % 5 == 0) {
+ dx = dx/5;
+ dy = dy/5;
+ cout << "Found modulus 5!" << endl;
+ }
+
+ coord newNode = a;
+ while (isInBounds(newNode)) {
+ resNodes.push_back(newNode);
+ newNode = {newNode.first - dx, newNode.second - dy};
+ }
+ newNode = {a.first + dx, a.second + dy};
+ while (isInBounds(newNode)) {
+ resNodes.push_back(newNode);
+ newNode = {newNode.first + dx, newNode.second + dy};
+ }
+ return resNodes;
+}
+
+int countAntinodes() {
+ int nantinodes = 0;
+ array<array<bool, 100>, 100> hasAntiNode = {false};
+
+ for (auto [key, freqbeacons] : beacons) {
+ for (int i = 0; i < freqbeacons.size(); i++) {
+ for (int j = i + 1; j < freqbeacons.size(); j++) {
+ auto [a, b] = antinodePositions(freqbeacons[i], freqbeacons[j]);
+ DEBUG && cout << "Beacons (" << freqbeacons[i].first << ", " << freqbeacons[i].second << ") and (" << freqbeacons[j].first << ", " << freqbeacons[j].second << ")" << endl;
+ if (isInBounds(a) && !hasAntiNode[a.first][a.second]) {
+ nantinodes++;
+ hasAntiNode[a.first][a.second] = true;
+ DEBUG && cout << "Antinode at " << a.first << " " << a.second << endl;
+ }
+ if (isInBounds(b) && !hasAntiNode[b.first][b.second]) {
+ nantinodes++;
+ hasAntiNode[b.first][b.second] = true;
+ DEBUG && cout << "Antinode at " << a.first << " " << a.second << endl;
+ }
+ }
+ }
+ }
+ return nantinodes;
+}
+
+bool printNodes(const array<array<bool, 100>, 100> &hasAntiNode) {
+ vector<string> grid;
+ for (int row = 0 ; row < nrows ; row++) {
+ grid.push_back("");
+ for (int col = 0; col < ncols; col++) {
+ if (hasAntiNode[row][col]) {
+ grid[row] += "#";
+ } else {
+ grid[row] += ".";
+ }
+ }
+ }
+ for (auto [key, freqbeacons] : beacons) {
+ for (auto beacon : freqbeacons) {
+ grid[beacon.first][beacon.second] = key;
+ }
+ }
+ for (auto row : grid) {
+ cout << row << endl;
+ }
+ return false;
+}
+
+int countFrequencyNodes() {
+ int nantinodes = 0;
+ array<array<bool, 100>, 100> hasAntiNode = {false};
+
+ for (auto [key, freqbeacons] : beacons) {
+ for (int i = 0; i < freqbeacons.size(); i++) {
+ for (int j = i + 1; j < freqbeacons.size(); j++) {
+ DEBUG && cout << key << "-beacons (" << freqbeacons[i].first << ", " << freqbeacons[i].second << ") and (" << freqbeacons[j].first << ", " << freqbeacons[j].second << ")" << endl;
+ DEBUG && cout << "Resonance nodes at ";
+ for (auto resNode : resonanceNodes(freqbeacons[i], freqbeacons[j])) {
+ DEBUG && cout << "(" << resNode.first << ", " << resNode.second << "), ";
+ if (!hasAntiNode[resNode.first][resNode.second]) {
+ nantinodes++;
+ hasAntiNode[resNode.first][resNode.second] = true;
+ }
+ }
+ DEBUG && cout << endl;
+ }
+ }
+ }
+ DEBUG && printNodes(hasAntiNode);
+ return nantinodes;
+}
+
+bool printBeacons() {
+ for (auto [key, freqbeacons] : beacons) {
+ cout << key << ": ";
+ for (auto beacon : freqbeacons) {
+ cout << "(" << beacon.first << ", " << beacon.second << ") ";
+ }
+ cout << endl;
+ }
+ return false;
+}
+
+int main () {
+ parseInput();
+ DEBUG && printBeacons();
+ cout << "Part 1: " << countAntinodes() << endl;
+ cout << "Part 2: " << countFrequencyNodes() << endl;
+ DEBUG && cout << "nrow: " << nrows << " ncols: " << ncols << endl;
+ return 0;
+}
\ No newline at end of file
diff --git a/day 9/day_9_felix.cpp b/day 9/day_9_felix.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..dc14694d24dd9d1e74df0ab7738d5fa9d363c164
--- /dev/null
+++ b/day 9/day_9_felix.cpp
@@ -0,0 +1,65 @@
+#include <bits/stdc++.h>
+using namespace std;
+const bool DEBUG = false;
+
+deque<long long> input;
+deque<long long> fwdOriginal;
+
+void readInput() {
+ char c;
+ long long i = 0;
+ bool iseven = true;
+ while (cin >> c) {
+ input.push_back(c-'0');
+ if (iseven){
+ for (int j=0; j<c-'0'; j++) fwdOriginal.push_back(i);
+ }
+ if (iseven) i++;
+ iseven = !iseven;
+ }
+}
+
+
+long long checkSum() {
+ deque<long long> fwd = fwdOriginal;
+ long long dig = 0;
+ long long hole = 0;
+
+ long long sum = 0;
+ long long pos = 0;
+ while (input.size() > 0) {
+ dig = input.front();
+ input.pop_front();
+ DEBUG && cout << "DIGIT " << dig << endl;
+ for (int i=0; i<dig; i++) {
+ long long val = fwd.front();
+ sum += pos * val;
+ DEBUG && cout << "Added " << val << " * " << pos << endl;
+ fwd.pop_front();
+ if (fwd.size() == 0) return sum;
+ pos++;
+ }
+
+ if (input.size() < 1) return sum;
+ hole = input.front();
+ input.pop_front();
+ DEBUG && cout << "HOLE" << endl;
+ for (int i=0; i<hole; i++) {
+ long long val = fwd.back();
+ sum += pos * val;
+ DEBUG && cout << "Added " << val << " * " << pos << endl;
+ fwd.pop_back();
+ if (fwd.size() == 0) return sum;
+ pos++;
+ }
+ }
+ return sum;
+}
+
+int main () {
+ readInput();
+
+ long long part1 = checkSum();
+ cout << "Part 1: " << part1 << endl;
+ return 0;
+}
\ No newline at end of file
diff --git a/day 9/day_9_felix2.cpp b/day 9/day_9_felix2.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..53676a6d50f6db3b04f5630185000a4cd03cb5cd
--- /dev/null
+++ b/day 9/day_9_felix2.cpp
@@ -0,0 +1,76 @@
+#include <bits/stdc++.h>
+using namespace std;
+const bool DEBUG = true;
+
+#define ll long long
+
+vector <ll> fileid;
+vector <ll> filesize;
+vector <ll> filestart;
+
+vector <ll> holestart;
+vector <ll> holesize;
+
+void readInput() {
+ char c;
+ ll i = 0;
+ bool iseven = true;
+ ll pos = 0;
+ while (cin >> c) {
+ if (iseven) {
+ fileid.push_back(i);
+ filesize.push_back(c-'0');
+ filestart.push_back(pos);
+ i++;
+ pos += c-'0';
+ } else {
+ holestart.push_back(pos);
+ holesize.push_back(c-'0');
+ pos += c-'0';
+ }
+ iseven = !iseven;
+ }
+}
+
+
+void rearrange() {
+ DEBUG && cout << "Rearranging files" << endl;
+
+ for (int file = filesize.size()-1; file >= 0; file--) {
+ for (int hole = 0; hole < file; hole++) {
+ if (holesize[hole] >= filesize[file]) {
+ // insert file into hole
+ DEBUG && cout << "Inserting file " << fileid[file] << " into hole pos " << holestart[hole] << endl;
+ holesize[hole] -= filesize[file];
+ filestart[file] = holestart[hole];
+ holestart[hole] += filesize[file];
+ break;
+ }
+ }
+ }
+}
+
+ll fileValue(int file) {
+ ll val = 0;
+ for (ll i = 0; i < filesize[file]; i++) {
+ val += filestart[file] + i;
+ }
+ return val * fileid[file];
+}
+
+ll checkSum() {
+ ll sum = 0;
+ for (int file = 0; file < fileid.size(); file++) {
+ sum += fileValue(file);
+ }
+ return sum;
+}
+
+int main () {
+ readInput();
+ rearrange();
+
+ long long part2 = checkSum();
+ cout << "Part 2: " << part2 << endl;
+ return 0;
+}
\ No newline at end of file