diff --git a/problems/0509.斐波那契数.md b/problems/0509.斐波那契数.md
index 1fa5ca18..69306801 100644
--- a/problems/0509.斐波那契数.md
+++ b/problems/0509.斐波那契数.md
@@ -214,6 +214,33 @@ class Solution:
             a, b = b, c
         return c
 
+# 动态规划 (注释版。无修饰)
+class Solution:
+    def fib(self, n: int) -> int:
+       
+        # 排除 Corner Case
+        if n == 1:
+            return 1
+
+        if n == 0:
+            return 0
+        
+        # 创建 dp table 
+        dp = [0] * (n + 1)
+
+        # 初始化 dp 数组
+        dp[0] = 0
+        dp[1] = 1
+
+        # 遍历顺序: 由前向后。因为后面要用到前面的状态
+        for i in range(2, n + 1):
+
+            # 确定递归公式/状态转移公式
+            dp[i] = dp[i - 1] + dp[i - 2]
+        
+        # 返回答案
+        return dp[n]
+
 # 递归实现
 class Solution:
     def fib(self, n: int) -> int: