750. [2018国庆雅礼集训10-6T1] Merchant

https://sjzezoj.com/submission/20508

S2OJ/750/750.cpp

@@ -0,0 +1,42 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, m, k[1000005], b[1000005];
+long long c[1000005], s, ans;
+
+bool check(int t) {
+    long long sum = 0;
+    for (int i = 0; i < n; i++) {
+        c[i] = 1ll * k[i] * t + b[i];
+    }
+    nth_element(c, c + m, c + n, greater<long long>());
+    for (int i = 0; i < m; i++) {
+        if (c[i] >= 0) sum += c[i];
+        if (sum >= s) return true;
+    }
+    return false;
+}
+
+int main() {
+    cin >> n >> m >> s;
+    for (int i = 0; i < n; i++) {
+        cin >> k[i] >> b[i];
+    }
+    if (check(0)) {
+        cout << 0 << endl;
+        exit(0);
+    }
+    int l = 0, r = 1e9 + 1;
+    while (l <= r) {
+        int mid = l + r >> 1;
+        if (check(mid)) {
+            r = mid - 1;
+            ans = mid;
+        } else {
+            l = mid + 1;
+        }
+    }
+    cout << ans << endl;
+    return 0;
+}