diff --git a/2112/211225.cpp b/2112/211225.cpp
new file mode 100644
index 0000000..43125af
--- /dev/null
+++ b/2112/211225.cpp
@@ -0,0 +1,56 @@
+#include <string>
+
+class Solution {
+public:
+	static int calculate(const std::string& s) {
+		int ret = 0;
+		char op = '+', prevOp = '+';
+		int n = 0, mid = 0;
+		for (const char c : s) {
+			if (c >= 0x30 && c <= 0x39) { n = (n << 3) + (n << 1) + (c ^ 48); }
+			else if (c == '+' || c == '-') {
+				switch (op) {
+					case '+':
+						ret += n; break;
+					case '-':
+						ret -= n; break;
+					case '*':
+						mid *= n; ret += prevOp == '+' ? mid : -mid; break;
+					case '/':
+						mid /= n; ret += prevOp == '+' ? mid : -mid; break;
+					default: exit(114514);
+				}
+				n = 0; op = c;
+			} else if (c == '*' || c == '/') {
+				switch (op) {
+					case '+':
+					case '-':
+						prevOp = op; mid = n; break;
+					case '*':
+						mid *= n; break;
+					case '/':
+						mid /= n; break;
+					default: exit(1919810);
+				}
+				n = 0; op = c;
+			}
+		}
+		switch (op) {
+			case '+':
+				ret += n; break;
+			case '-':
+				ret -= n; break;
+			case '*':
+				mid *= n; ret += prevOp == '+' ? mid : -mid; break;
+			case '/':
+				mid /= n; ret += prevOp == '+' ? mid : -mid; break;
+			default: exit(114514);
+		}
+		return ret;
+	}
+};
+
+int main() {
+	std::printf("%d\n", Solution::calculate("-1-2*3+4/5"));
+	return 0;
+}
diff --git a/2112/CMakeLists.txt b/2112/CMakeLists.txt
index 40e981d..45e8cef 100644
--- a/2112/CMakeLists.txt
+++ b/2112/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2112)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2112 211224.cpp)
\ No newline at end of file
+ADD_EXECUTABLE(2112 211225.cpp)
\ No newline at end of file