diff --git a/13zsk.py.py b/13zsk.py.py
new file mode 100644
index 0000000..aa820fe
--- /dev/null
+++ b/13zsk.py.py
@@ -0,0 +1,50 @@
+s = "Hello"
+for c in s:
+    print(c, ord(c))
+print(chr(65))
+
+# ========== 题目3 ==========
+A = [3, 4]
+B = [1, 2]
+
+# 1. 向量加法
+def vector_add(a, b):
+    return [x + y for x, y in zip(a, b)]
+
+# 2. 数乘向量
+def scalar_multiply(scalar, vec):
+    return [scalar * x for x in vec]
+
+# 3. 计算向量的模
+def vector_norm(vec):
+    return sum(x**2 for x in vec) ** 0.5
+
+print("题目3：")
+print(f"1. A + B = {vector_add(A, B)}")
+print(f"2. 2 × A = {scalar_multiply(2, A)}")
+print(f"3. A的模 = {vector_norm(A)}")
+
+print("-" * 30)
+
+# ========== 题目4 ==========
+A1 = [1, 2, 3]
+B1 = [4, 5, 6]
+A2 = [1, 0]
+B2 = [0, 1]
+
+# 1. 点积计算
+def dot_product(a, b):
+    return sum(x * y for x, y in zip(a, b))
+
+# 2. 余弦相似度计算
+def cosine_similarity(a, b):
+    dot = dot_product(a, b)
+    norm_a = vector_norm(a)
+    norm_b = vector_norm(b)
+    return dot / (norm_a * norm_b) if norm_a != 0 and norm_b != 0 else 0
+
+print("题目4：")
+print(f"1. A·B = {dot_product(A1, B1)}")
+print(f"2. A1与B1的余弦相似度 = {cosine_similarity(A1, B1):.4f}")
+print(f"3. A2与B2的余弦相似度 = {cosine_similarity(A2, B2)}")
+print("   原因：两个向量正交（点积为0），方向完全垂直，所以相似度为0")
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