diff --git a/day7/CMakeLists.txt b/day7/CMakeLists.txt
new file mode 100644
index 0000000..f6872a6
--- /dev/null
+++ b/day7/CMakeLists.txt
@@ -0,0 +1,29 @@
+cmake_minimum_required(VERSION 3.10)
+
+# Project name and version
+project(Day7 VERSION 1.0)
+
+# Set default build type
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE Debug)
+endif()
+
+# 1. This is the critical line for Clangd. 
+# It generates the file clangd reads to know where headers are.
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# Debug and Release flags
+set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g -O0 -Wall -Wextra")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3")
+
+# Specify C standard
+set(CMAKE_CXX_STANDARD 23)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Add include directory
+include_directories(${PROJECT_SOURCE_DIR}/include)
+
+# Add executable
+add_executable(${PROJECT_NAME} 
+    src/main.cpp
+)
diff --git a/day7/Makefile b/day7/Makefile
new file mode 100644
index 0000000..48caf0c
--- /dev/null
+++ b/day7/Makefile
@@ -0,0 +1,13 @@
+
+
+clear:
+	rm -rf build/*
+
+run:
+	cp input.txt build
+	cp input_test.txt build
+	cd build && cmake .. && make && ./Day7 input_test.txt
+
+release:
+	cp input.txt build
+	cd build && cmake .. -DCMAKE_BUILD_TYPE=Release && make && ./Day7 input.txt
diff --git a/day7/flake.lock b/day7/flake.lock
new file mode 100644
index 0000000..2b1bdda
--- /dev/null
+++ b/day7/flake.lock
@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1756787288,
+        "narHash": "sha256-rw/PHa1cqiePdBxhF66V7R+WAP8WekQ0mCDG4CFqT8Y=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "d0fc30899600b9b3466ddb260fd83deb486c32f1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/day7/flake.nix b/day7/flake.nix
new file mode 100644
index 0000000..20aa75f
--- /dev/null
+++ b/day7/flake.nix
@@ -0,0 +1,58 @@
+{
+  description = "A Nix-flake-based C/C++ development environment";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs =
+    { self, nixpkgs }:
+    let
+      supportedSystems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+      forEachSupportedSystem =
+        f:
+        nixpkgs.lib.genAttrs supportedSystems (
+          system:
+          f {
+            pkgs = import nixpkgs { inherit system; };
+          }
+        );
+    in
+    {
+      devShells = forEachSupportedSystem (
+        { pkgs }:
+        {
+          default =
+            pkgs.mkShell.override
+              {
+                # Override stdenv in order to change compiler:
+                # stdenv = pkgs.clangStdenv;
+              }
+
+              {
+                nativeBuildInputs = with pkgs; [
+                  pkg-config
+                ];
+                packages =
+                  with pkgs;
+                  [
+                    clang-tools
+                    cmake
+                    codespell
+                    cppcheck
+                    doxygen
+                    gtest
+                    lcov
+                    nodejs
+                    vscode-extensions.vadimcn.vscode-lldb
+                  ]
+                  ++ (if system == "aarch64-darwin" then [ ] else [ gdb ]);
+                CODELLDB_PATH = "${pkgs.vscode-extensions.vadimcn.vscode-lldb}/share/vscode/extensions/vadimcn.vscode-lldb/adapter/codelldb";
+              };
+        }
+      );
+    };
+}
diff --git a/day7/input_test.txt b/day7/input_test.txt
new file mode 100644
index 0000000..57a2466
--- /dev/null
+++ b/day7/input_test.txt
@@ -0,0 +1,16 @@
+.......S.......
+...............
+.......^.......
+...............
+......^.^......
+...............
+.....^.^.^.....
+...............
+....^.^...^....
+...............
+...^.^...^.^...
+...............
+..^...^.....^..
+...............
+.^.^.^.^.^...^.
+...............
diff --git a/day7/src/main.cpp b/day7/src/main.cpp
new file mode 100644
index 0000000..6afb5a7
--- /dev/null
+++ b/day7/src/main.cpp
@@ -0,0 +1,141 @@
+#include <cmath>
+#include <cstdlib>
+#include <fstream>
+#include <iomanip>
+#include <iostream>
+#include <sys/types.h>
+#include <vector>
+
+typedef long melem;
+typedef std::vector<std::vector<melem>> Matrix;
+
+void print_matrix(const Matrix &matrix) {
+  for (const auto &row : matrix) {
+    for (const auto &cell : row) {
+      std::cout << std::setw(4) << static_cast<melem>(cell) << ' ';
+    }
+    std::cout << std::endl;
+  }
+}
+
+long compute_splits_part2(Matrix &matrix, int row_pos, int col_pos) {
+  for (int i = row_pos + 1; i < matrix.size(); i++) {
+    if (matrix[i][col_pos] == 1) {
+      if (col_pos > 0) {
+        matrix[i][col_pos] = compute_splits_part2(matrix, i, col_pos - 1);
+      }
+      if (col_pos < matrix[i].size() - 1) {
+        matrix[i][col_pos] += compute_splits_part2(matrix, i, col_pos + 1);
+      }
+      return matrix[i][col_pos];
+    }
+    if (matrix[i][col_pos] > 1)
+      return matrix[i][col_pos];
+  }
+  return 1;
+}
+
+long compute_num_splits(Matrix &matrix, int row_pos, int col_pos) {
+  if (matrix[row_pos][col_pos] == -1) {
+    return 0;
+  }
+  for (int i = row_pos + 1; i < matrix.size(); i++) {
+    if (matrix[i][col_pos] == -1)
+      return 0;
+    if (matrix[i][col_pos] == 1) {
+      if (col_pos > 0) {
+        matrix[i][col_pos] += compute_num_splits(matrix, i, col_pos - 1);
+      }
+      if (col_pos < matrix[i].size() - 1) {
+        matrix[i][col_pos] += compute_num_splits(matrix, i, col_pos + 1);
+      }
+      return matrix[i][col_pos];
+    }
+    matrix[i][col_pos] = -1;
+  }
+  return matrix[row_pos][col_pos];
+}
+
+long compute_score(Matrix &matrix, bool do_part2) {
+  int row_pos = -1, col_pos = -1;
+  for (size_t i = 0; i < matrix.size(); i++) {
+    for (size_t j = 0; j < matrix[i].size(); j++) {
+      if (matrix[i][j] == 1) {
+        // found the first splitter
+        row_pos = i;
+        col_pos = j;
+        break;
+      }
+    }
+    if (row_pos != -1 || col_pos != -1)
+      break;
+  }
+
+  if (row_pos == -1 || col_pos == -1) {
+    std::cerr << "No splitter found in the matrix." << std::endl;
+    return -1;
+  }
+  if (!do_part2) {
+    matrix[row_pos][col_pos] +=
+        compute_num_splits(matrix, row_pos, col_pos - 1);
+    matrix[row_pos][col_pos] +=
+        compute_num_splits(matrix, row_pos, col_pos + 1);
+  } else {
+    matrix[row_pos][col_pos] =
+        compute_splits_part2(matrix, row_pos, col_pos - 1);
+    matrix[row_pos][col_pos] +=
+        compute_splits_part2(matrix, row_pos, col_pos + 1);
+  }
+  return matrix[row_pos][col_pos];
+}
+
+Matrix parse_file(const std::string &path) {
+  std::ifstream file;
+  std::string line;
+  Matrix matrix;
+
+  file.open(path);
+  if (!file.is_open()) {
+    std::cerr << "Error opening file: " << path << std::endl;
+    return matrix;
+  }
+  while (std::getline(file, line)) {
+    std::vector<melem> row(line.length(), 0);
+    for (int i = 0; i < line.length(); i++) {
+      char c = line[i];
+      if (c == '.') {
+        row[i] = 0;
+      } else if (c == '^') {
+        row[i] = 1;
+      } else if (c == 'S') {
+        row[i] = -1;
+      }
+    }
+    matrix.emplace_back(row);
+  }
+
+  file.close();
+  return matrix;
+}
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    std::cout << "One argument required: input txt" << std::endl;
+  }
+  auto matrix = parse_file(argv[1]);
+  auto matrix_copy(matrix);
+
+  std::cout << "Matrix before computing" << std::endl;
+  print_matrix(matrix);
+  melem score = compute_score(matrix, false);
+
+  std::cout << "Matrix after computing" << std::endl;
+  print_matrix(matrix);
+  std::cout << "part 1 " << score << std::endl;
+
+  score = compute_score(matrix_copy, true);
+  print_matrix(matrix_copy);
+  std::cout << "part 2 " << score << std::endl;
+
+  return 0;
+}