diff --git a/TangDou/Topic/【前缀和与差分】题单.md b/TangDou/Topic/【前缀和与差分】题单.md
index 5951421..65c2a35 100644
--- a/TangDou/Topic/【前缀和与差分】题单.md
+++ b/TangDou/Topic/【前缀和与差分】题单.md
@@ -340,7 +340,39 @@ int main() {
 
 就和$P1115$的做法一样了！
 
+**$Code$**
+
+```cpp {.line-numbers}
+#include <bits/stdc++.h>
+using namespace std;
+
+const int N = 330;
+int n;
+int a[N][N], s[N][N], dp[N];
+int res = INT_MIN;
+
+int main() {
+    cin >> n;
+    // 前缀和(竖直方向)
+    for (int i = 1; i <= n; i++)
+        for (int j = 1; j <= n; j++) {
+            cin >> a[i][j];
+            s[i][j] = s[i - 1][j] + a[i][j]; // 一维前缀和，这可不是二维前缀和
+        }
+
+    // 降维变成一维dp
+    for (int i = 0; i <= n - 1; i++)       // 枚举左上角
+        for (int j = i + 1; j <= n; j++)   // 枚举右下角
+            for (int k = 1; k <= n; k++) { // 枚举每一列
+                dp[k] = max(s[j][k] - s[i][k], dp[k - 1] + s[j][k] - s[i][k]);
+                res = max(res, dp[k]);
+            }
+    // 输出
+    cout << res << endl;
+    return 0;
+}
 
+```
 
 #### [$P2004$ 领地选择](https://www.luogu.com.cn/problem/P2004)