P4571 [JSOI2009] 瓶子和燃料

https://www.luogu.com.cn/record/89424858

Luogu/P4571/P4571.cpp

@@ -0,0 +1,38 @@
+#include <iostream>
+#include <map>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+int n, k;
+std::map<int, int> map;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> k;
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> x;
+
+        for (int j = 1; j * j <= x; j++) {
+            if (x % j == 0) {
+                map[j]++;
+
+                if (j != x / j) map[x / j]++;
+            }
+        }
+    }
+
+    for (auto it = map.rbegin(); it != map.rend(); it++) {
+        if (it->second >= k) {
+            cout << it->first << endl;
+
+            exit(0);
+        }
+    }
+
+    return 0;
+}