Create 100819L_Standard.cpp

Codeforces/Gym/100819L_Standard.cpp

@@ -0,0 +1,38 @@
+#include <iostream>
+#include <iomanip>
+#include <cmath>
+
+using namespace std;
+
+const int MAXN = 100000;
+int N, W;
+string safe;
+long double p[MAXN], v[MAXN+1], s[MAXN+1];
+
+int main()
+{
+    //ios::sync_with_stdio(0);
+    while (cin >> N >> W && N)
+    {
+        v[0] = 0;
+        for (int i = 0; i < N; ++i)
+        {
+            cin >> safe >> p[i] >> v[i+1];
+            v[i+1] = log1p(v[i+1] / W);
+            if (safe == "safe")
+                s[i+1] = v[i+1];
+            else
+                s[i+1] = s[i];
+        }
+        for (int i = N-1; i >= 0; --i)
+        {
+            long double Ewin = p[i]*v[i+1] + (1-p[i])*s[i];
+            v[i] = max(v[i], Ewin);
+        }
+        long double ans = expm1(v[0]) * W;
+        cout << '$' << fixed << setprecision(2) << ans << endl;
+        int residualDigit = int(1000*ans) % 10;
+        if (residualDigit == 4 || residualDigit == 5)
+            cerr << "WARNING: " << residualDigit << " in the first unseen place" << endl;
+    }
+}