C - Coupon

https://atcoder.jp/contests/abc246/submissions/30648451

AtCoder/ABC246/C/C.cpp

@@ -0,0 +1,48 @@
+#include <algorithm>
+#include <cmath>
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e5 + 5;
+
+int n, k, x, a[N];
+long long sum;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n >> k >> x;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+        sum += a[i];
+    }
+
+    std::sort(a + 1, a + 1 + n, std::greater<int>());
+    for (int i = 1, t; i <= n; i++) {
+        if (a[i] < x) break;
+
+        t = a[i] / x;
+        a[i] %= x;
+
+        if (k > t) {
+            k -= t;
+            sum -= t * x;
+        } else {
+            sum -= k * x;
+            cout << sum << endl;
+            exit(0);
+        }
+    }
+
+    std::sort(a + 1, a + 1 + n, std::greater<int>());
+    for (int i = 1; i <= std::min(n, k); i++) {
+        sum -= a[i];
+    }
+
+    cout << sum << endl;
+
+    return 0;
+}