diff --git a/TangDou/Topic/PrefixAndSuffix/P1719_1.cpp b/TangDou/Topic/PrefixAndSuffix/P1719_1.cpp
index f7da2e9..5f79f3b 100644
--- a/TangDou/Topic/PrefixAndSuffix/P1719_1.cpp
+++ b/TangDou/Topic/PrefixAndSuffix/P1719_1.cpp
@@ -2,17 +2,15 @@
 using namespace std;
 const int N = 130;
 int n;
-int a[N][N];  // 存储题目中的矩阵
-int s[N][N];  // 二维前缀和
-int qz[N][N]; // qz[i][j]指的是第i行到j的前缀和
+int a[N][N]; // 存储题目中的矩阵
+int s[N][N]; // 二维前缀和
 
 int main() {
     cin >> n;
     for (int i = 1; i <= n; i++) {
         for (int j = 1; j <= n; j++) {
             cin >> a[i][j];
-            qz[i][j] = qz[i][j - 1] + a[i][j]; // 求前缀和
-            s[i][j] = qz[i][j] + s[i - 1][j];  // 计算s
+            s[i][j] = s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1] + a[i][j];
         }
     }