Add initial project files including CMake configuration, Python extractor, and CUDA implementation

src/main.cu

@@ -0,0 +1,162 @@
+#include <vector>
+#include <fstream>
+#include <sstream>
+#include <iostream>
+#include <cuda_runtime.h>
+#include <algorithm>
+#include <chrono>
+
+__global__ void find_nearest_B(
+    const float3 *__restrict__ A,
+    const float3 *__restrict__ B,
+    int *nearest_idx,
+    int N, int M)
+{
+    int idx = blockDim.x * blockIdx.x + threadIdx.x;
+    if (idx >= N)
+        return;
+
+    float3 a = A[idx];
+    float min_dist = 1e30f;
+    int min_j = -1;
+
+    for (int j = 0; j < M; ++j)
+    {
+        float dx = a.x - B[j].x;
+        float dy = a.y - B[j].y;
+        float dz = a.z - B[j].z;
+        float dist = dx * dx + dy * dy + dz * dz;
+
+        if (dist < min_dist)
+        {
+            min_dist = dist;
+            min_j = j;
+        }
+    }
+
+    nearest_idx[idx] = min_j;
+}
+
+std::vector<float3> load_coords_from_file(const std::string &filename)
+{
+    std::vector<float3> coords;
+    std::ifstream file(filename);
+    if (!file)
+    {
+        std::cerr << "Unable to open file: " << filename << std::endl;
+        return coords;
+    }
+
+    std::string line;
+    while (std::getline(file, line))
+    {
+        std::istringstream iss(line);
+        float x, y, z;
+        if (iss >> x >> y >> z)
+        {
+            coords.push_back(make_float3(x, y, z));
+        }
+    }
+
+    return coords;
+}
+
+void save_results_sorted(const std::string &filename,
+                         const std::vector<float3> &h_A,
+                         const std::vector<float3> &h_B,
+                         const std::vector<int> &indices)
+{
+    struct Entry
+    {
+        float ax, az;
+        float bx, bz;
+        float dist;
+    };
+
+    std::vector<Entry> entries;
+
+    for (size_t i = 0; i < indices.size(); ++i)
+    {
+        float3 a = h_A[i];
+        float3 b = h_B[indices[i]];
+
+        float dx = a.x - b.x;
+        float dy = a.y - b.y;
+        float dz = a.z - b.z;
+        float dist = sqrtf(dx * dx + dy * dy + dz * dz);
+
+        entries.push_back({a.x, a.z, b.x, b.z, dist});
+    }
+
+    std::sort(entries.begin(), entries.end(), [](const Entry &e1, const Entry &e2)
+              { return e1.dist < e2.dist; });
+
+    std::ofstream file(filename);
+    for (const auto &e : entries)
+    {
+        file << e.ax << " " << e.az << "  "
+             << e.bx << " " << e.bz << "  "
+             << e.dist << std::endl;
+    }
+}
+
+int main()
+{
+    auto t_start = std::chrono::high_resolution_clock::now();
+
+    std::vector<float3> h_A = load_coords_from_file("data/cities.txt");
+    std::vector<float3> h_B = load_coords_from_file("data/strongholds.txt");
+
+    int N = h_A.size();
+    int M = h_B.size();
+
+    if (N == 0 || M == 0)
+    {
+        std::cerr << "Coords empty." << std::endl;
+        return 1;
+    }
+
+    float3 *d_A;
+    float3 *d_B;
+    int *d_nearest_idx;
+    cudaMalloc(&d_A, sizeof(float3) * N);
+    cudaMalloc(&d_B, sizeof(float3) * M);
+    cudaMalloc(&d_nearest_idx, sizeof(int) * N);
+
+    cudaMemcpy(d_A, h_A.data(), sizeof(float3) * N, cudaMemcpyHostToDevice);
+    cudaMemcpy(d_B, h_B.data(), sizeof(float3) * M, cudaMemcpyHostToDevice);
+
+    int threads = 256;
+    int blocks = (N + threads - 1) / threads;
+
+    // ✅ CUDA 커널 시간 측정 시작
+    cudaEvent_t start, stop;
+    cudaEventCreate(&start);
+    cudaEventCreate(&stop);
+    cudaEventRecord(start);
+
+    find_nearest_B<<<blocks, threads>>>(d_A, d_B, d_nearest_idx, N, M);
+
+    cudaEventRecord(stop);
+    cudaEventSynchronize(stop);
+    float milliseconds = 0;
+    cudaEventElapsedTime(&milliseconds, start, stop);
+    std::cout << "CUDA kernel time: " << milliseconds << " ms" << std::endl;
+
+    std::vector<int> h_nearest_idx(N);
+    cudaMemcpy(h_nearest_idx.data(), d_nearest_idx, sizeof(int) * N, cudaMemcpyDeviceToHost);
+
+    save_results_sorted("output.txt", h_A, h_B, h_nearest_idx);
+
+    cudaFree(d_A);
+    cudaFree(d_B);
+    cudaFree(d_nearest_idx);
+
+    auto t_end = std::chrono::high_resolution_clock::now();
+    std::chrono::duration<double> elapsed = t_end - t_start;
+    std::cout << "Total time: " << elapsed.count() * 1000.0 << " ms" << std::endl;
+
+    std::cout << "Saved to output.txt." << std::endl;
+
+    return 0;
+}