diff --git a/.vscode/launch.json b/.vscode/launch.json
index de9bd5a..356814a 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -5,7 +5,7 @@
             "name": "nyplaylists",
             "type": "cppdbg",
             "request": "launch",
-            "program": "${fileDirname}/${fileBasenameNoExtension}", // 指向你的可执行文件
+            "program": "${fileDirname}/${fileBasenameNoExtension}",
             "args": [
                 "playlist_tiny2.txt",
                 "actions2.txt",
@@ -17,6 +17,41 @@
             "MIMode": "gdb",
             "miDebuggerPath": "/usr/bin/gdb",
             "preLaunchTask": "C/C++: g++ build active file"
+        },
+        {
+            "name": "nyride",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "${fileDirname}/${fileBasenameNoExtension}",
+            "args": [
+                "drivers.txt",
+                "riders.txt",
+                "output0.txt",
+                "output1.txt",
+                "output2.txt",
+                "516-951-1561",
+                "request",
+                "debug"
+            ],
+            "cwd": "${fileDirname}",
+            "environment": [],
+            "MIMode": "gdb",
+            "miDebuggerPath": "/usr/bin/gdb",
+            "preLaunchTask": "C/C++: g++ build active file"
+        },
+        {
+            "name": "lab02-roads",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "${fileDirname}/${fileBasenameNoExtension}",
+            "args": [
+                "input_a.txt"
+            ],
+            "cwd": "${fileDirname}",
+            "environment": [],
+            "MIMode": "gdb",
+            "miDebuggerPath": "/usr/bin/gdb",
+            "preLaunchTask": "C/C++: g++ build active file"
         }
     ]
 }
diff --git a/labs/debugging/line.cpp b/labs/debugging/line.cpp
index 5a6a867..6f73589 100644
--- a/labs/debugging/line.cpp
+++ b/labs/debugging/line.cpp
@@ -22,7 +22,7 @@ double gradient(const Line &ln) {
   float gradient = 100.0 * fabs(slope);
   // take the absolute value
   if (gradient < 0) {
-    gradient * -1;
+    gradient *= -1;
   }
   return gradient;
 }
@@ -37,6 +37,5 @@ bool steeper_gradient(const Line &m, const Line &n) {
     return true;
   if (gradient_n > gradient_m)
     return false;
+  return false;
 }
-
-
diff --git a/labs/debugging/line.h b/labs/debugging/line.h
index 8c35b5f..08dc1e4 100644
--- a/labs/debugging/line.h
+++ b/labs/debugging/line.h
@@ -1,3 +1,5 @@
+#ifndef LINE_H
+#define LINE_H
 #include "point.h"
 
 // A simple line class.  In this simple world, we'll follow the
@@ -26,4 +28,4 @@ double gradient(const Line &ln);
 // (That can be used to sort a collection of roads.)
 bool steeper_gradient(const Line &m, const Line &n);
 
-
+#endif
\ No newline at end of file
diff --git a/labs/debugging/main b/labs/debugging/main
deleted file mode 100755
index 76b814c..0000000
Binary files a/labs/debugging/main and /dev/null differ
diff --git a/labs/debugging/main.cpp b/labs/debugging/main.cpp.back
similarity index 100%
rename from labs/debugging/main.cpp
rename to labs/debugging/main.cpp.back
diff --git a/labs/debugging/point.cpp b/labs/debugging/point.cpp
index 552ac82..891b612 100644
--- a/labs/debugging/point.cpp
+++ b/labs/debugging/point.cpp
@@ -20,6 +20,6 @@ double compute_slope(const Point &a, const Point &b) {
   double run_x = b.get_x() - a.get_x();
   double run_z = b.get_z() - a.get_z();
   double run = sqrt(run_x*run_x + run_z*run_z);
-  double answer = rise / run;
+  //double answer = rise / run;
   return rise / run;
 }
diff --git a/labs/debugging/point.h b/labs/debugging/point.h
index a70eae6..1d1cab0 100644
--- a/labs/debugging/point.h
+++ b/labs/debugging/point.h
@@ -1,6 +1,7 @@
+#ifndef _POINT_H_
+#define _POINT_H_
 #include <iostream>
 
-
 // A simple 3D point class.  In this simple world, we'll follow the
 // convention often used in Computer Graphics.  y is the vertical
 // axes, "pointing" up.  The x and z axes define the ground plane.
@@ -26,3 +27,5 @@ std::ostream& operator<< (std::ostream &ostr, const Point &p);
 
 // A helper function to compute the slope between two Points.
 double compute_slope(const Point &a, const Point &b);
+
+#endif
\ No newline at end of file
diff --git a/labs/debugging/roads.cpp b/labs/debugging/roads.cpp
index a80274a..a7d4d45 100644
--- a/labs/debugging/roads.cpp
+++ b/labs/debugging/roads.cpp
@@ -2,13 +2,13 @@
 #include <vector>
 #include <cmath>
 #include <fstream>
+#include <algorithm>
 
 #include "line.h"
-
-
+#include "point.h"
 
 // A helper function to parse a collection of files from an input file.
-std::vector<Line>& load(std::ifstream &istr) {
+std::vector<Line> load(std::ifstream &istr) {
   std::vector<Line> roads;
   float x1,y1,z1,x2,y2,z2;
   while (istr >> x1 >> y1 >> z1 >> x2 >> y2 >> z2) {
@@ -28,13 +28,14 @@ void organize(std::vector<Line> &roads) {
 void print(const std::vector<Line> &roads) {
 
   // print each road in the current, sorted order (steepest first)
-  for (int i = 0; i < roads.size(); i++) {
+  //for (int i = 0; i < roads.size(); i++) {
+  for (size_t i = 0; i < roads.size(); i++) {
     std::cout << roads[i] << std::endl;
   }
 
   // count the number of roads with gradient less than 10%
   int count;
-  for (unsigned int i = roads.size() - 1;
+  for (int i = roads.size() - 1;
        i >= 0  && gradient(roads[i]) < 10.0;
        i--) {
     count++;