new file: helloworld.py

deleted:    nst/1.jpg
	deleted:    nst/img/gui.gif
	deleted:    nst/img/gui.jpg
	new file:   "nst/\351\241\271\347\233\256\346\212\245\345\221\212.pdf"

helloworld.py

@@ -0,0 +1,15 @@
+import cv2
+
+def detect_cameras(max_cameras=10):
+    cameras = []
+    for i in range(max_cameras):
+        cap = cv2.VideoCapture(i)
+        if cap is None or not cap.isOpened():
+            cap.release()
+        else:
+            cameras.append(i)
+            cap.release()
+    return cameras
+
+available_cameras = detect_cameras()
+print(f'Found {len(available_cameras)} camera(s): {available_cameras}')