完成 q4_3 评分+时长直方图

q4/q4_3b/q4_3b.py

@@ -0,0 +1,21 @@
+# q4_3b.py
+import json
+import matplotlib.pyplot as plt
+
+with open("../q4_2/movies.json", "r", encoding="utf-8") as f:
+    data = json.load(f)
+
+movies = data["movies"]
+
+durations = []
+for m in movies:
+    durations.append(m["duration"])
+
+plt.hist(durations, bins=5, color="green")
+plt.title("时长分布")
+plt.xlabel("时长（分钟）")
+
+plt.savefig("q4_3b_hist.png", dpi=150)
+plt.close()
+
+print("✅ 时长直方图生成成功！")