upload some new code

FZOI/计算器的改良.cpp

@@ -0,0 +1,57 @@
+#include <iostream>
+#include <cstdio>
+using namespace std;
+char c, a;
+int f = 1, now = 1, k, b, x;
+bool r;
+int main()
+{
+    while (cin >> c)
+    {
+        if (c == '-')
+        {
+            b += now * f * x;
+            x = 0;
+            f = -1;
+            r = 0;
+        }
+        if (c == '+')
+        {
+            b += now * f * x;
+            x = 0;
+            f = 1;
+            r = 0;
+        }
+        if (c == '=')
+        {
+            b += now * f * x;
+            x = 0;
+            f = 1;
+            now = -1;
+            r = 0;
+        }
+        if (c >= 'a' && c <= 'z')
+        {
+            if (r)
+            {
+                k += now * f * x;
+                x = 0;
+            }
+            else
+                k += now * f;
+            a = c;
+            r = 0;
+        }
+        if (c >= '0' && c <= '9')
+        {
+            x = x * 10 + c - '0';
+            r = 1;
+        }
+    }
+    b += now * f * x;
+    double ans = double(-b * 1.0 / k);
+    if (ans == -0.0)
+        ans = 0;
+    printf("%c=%.3lf", a, ans);
+    return 0;
+}