new file: P11681.cpp

P11681.cpp

@@ -0,0 +1,28 @@
+#include<bits/stdc++.h>
+using namespace std;
+const int mod = 1145141923;
+int n, m;
+int a[1000005];
+unordered_map<int, bool> ma;
+int _0;
+int main() {
+    scanf("%d%d", &n, &m);
+    for(int i = 1; i <= n; ++i) {
+        scanf("%d", &a[i]);
+        if(a[i]) {
+            if(!ma[a[i]]) ma[a[i]] = 1;
+            else {
+                printf("0\n");
+                return 0;
+            }
+        } else {
+            _0++;
+        }
+    }
+    long long ans = 1;
+    for(int i = m - n + _0; i > m - n; --i) {
+        ans = (ans * i) % mod;
+    }
+    printf("%lld\n", ans);
+    return 0;
+}