feat: add quiz 3 cross-checker.

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.10)
-project(plct_lab)
+project(plct-lab)
 
 set(CMAKE_CXX_STANDARD 11)
 
@@ -7,3 +7,4 @@ add_subdirectory(third-party/googletest-1.17.0)
 
 add_subdirectory(mixplus)
 add_subdirectory(counter)
+add_subdirectory(cross-checker)

README.md

@@ -0,0 +1,18 @@
+# PLCT LAT TEST
+
+## Build
+
+```bash
+make build
+cd build
+cmake ..
+make
+```
+
+Three test will be in:
+
+- mixplus
+- counter
+- cross-checker
+
+There are unit-tests implemented by gtest.

counter/include/counter.h

@@ -1,3 +1,4 @@
+#pragma once
 #include <string>
 #include <unordered_map>
 

cross-checker/CMakeLists.txt

@@ -0,0 +1,11 @@
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
+
+aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR}/src SRC)
+
+add_library(libcross-checker STATIC ${SRC})
+
+add_executable(cross-checker main.cpp)
+
+target_link_libraries(cross-checker libcross-checker)
+
+add_subdirectory(tests)

cross-checker/include/cross-checker.h

@@ -0,0 +1,38 @@
+//
+// Created by ricardo on 19/05/25.
+//
+
+#ifndef CROSS_CHECKER_H
+#define CROSS_CHECKER_H
+
+namespace cross_checker
+{
+    // 既可以表示点也可以表示一个向量
+    struct Point
+    {
+        double x;
+        double y;
+
+        Point(const double a, const double b) : x(a), y(b)
+        {
+        }
+
+        static int orientation(const Point& p, const Point& q, const Point& r);
+
+        static bool onSegment(const Point& p, const Point& q, const Point& r);
+    };
+
+    struct Line
+    {
+        Point startPoint;
+        Point endPoint;
+
+        Line(const Point a, const Point b): startPoint(a), endPoint(b)
+        {
+        }
+
+        bool intersect(const Line& other);
+    };
+}
+
+#endif //CROSS_CHECKER_H

cross-checker/main.cpp

@@ -0,0 +1,24 @@
+#include <cross-checker.h>
+#include <iostream>
+
+int main(int argc, char** argv)
+{
+    if (argc != 9)
+    {
+        std::cout << "ERROR: 4 point must be provided" << std::endl;
+    }
+
+    cross_checker::Line line1(cross_checker::Point(std::stod(argv[1]), std::stod(argv[2])), cross_checker::Point(
+                                  std::stod(argv[3]), std::stod(argv[4])));
+    cross_checker::Line line2(cross_checker::Point(std::stod(argv[5]), std::stod(argv[6])), cross_checker::Point(
+                                  std::stod(argv[7]), std::stod(argv[8])));
+
+    if (line1.intersect(line2))
+    {
+        std::cout << "TRUE" << std::endl;
+    }
+    else
+    {
+        std::cout << "FALSE" << std::endl;
+    }
+}

cross-checker/src/cross-checker.cpp

@@ -0,0 +1,58 @@
+#include <cmath>
+#include <algorithm>
+#include "cross-checker.h"
+
+
+// 计算向量叉积的方向
+// 返回值：
+//   0 表示三点共线
+//   1 表示逆时针方向（正）
+//  -1 表示顺时针方向（负）
+int cross_checker::Point::orientation(const Point& p, const Point& q, const Point& r)
+{
+    const double val = (q.x - p.x) * (r.y - p.y) - (r.x - p.x) * (q.y - p.y);
+    if (std::fabs(val) < 1e-9) return 0; // 共线
+    return (val > 0) ? 1 : -1;
+}
+
+bool cross_checker::Point::onSegment(const Point& p, const Point& q, const Point& r)
+{
+    return q.x <= std::max(p.x, r.x) && q.x >= std::min(p.x, r.x) &&
+        q.y <= std::max(p.y, r.y) && q.y >= std::min(p.y, r.y);
+}
+
+bool cross_checker::Line::intersect(const Line& other)
+{
+    const int o1 = Point::orientation(startPoint, endPoint, other.startPoint);
+    const int o2 = Point::orientation(startPoint, endPoint, other.endPoint);
+    const int o3 = Point::orientation(other.startPoint, other.endPoint, startPoint);
+    const int o4 = Point::orientation(other.startPoint, other.endPoint, endPoint);
+
+    // 普通情况：跨立实验
+    if (o1 != o2 && o3 != o4)
+    {
+        return true;
+    }
+
+    // 特殊情况：共线
+    if (o1 == 0 && Point::onSegment(startPoint, other.startPoint, endPoint))
+    {
+        return true;
+    }
+    if (o2 == 0 && Point::onSegment(startPoint, other.endPoint, endPoint))
+    {
+        return true;
+    }
+    if (o3 == 0 && Point::onSegment(other.startPoint, startPoint, other.endPoint))
+    {
+        return true;
+    }
+    if (o4 == 0 && Point::onSegment(other.startPoint, endPoint, other.endPoint))
+    {
+        return true;
+    }
+
+    return false;
+}
+
+

cross-checker/tests/CMakeLists.txt

@@ -0,0 +1,10 @@
+enable_testing()
+
+aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR} TEST_SRC)
+
+add_executable(
+        cross-checker-tests
+        ${TEST_SRC}
+)
+
+target_link_libraries(cross-checker-tests GTest::gtest_main libcount)