new file: P17311.cpp

P17311.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+using namespace std;
+int t;
+int n, k;
+int a[200005];
+int main() {
+    scanf("%d", &t);
+    while (t--) {
+        scanf("%d%d", &n, &k);
+        for (int i = 1; i <= n; ++i) {
+            scanf("%d", &a[i]);
+        }
+        sort(a + 1, a + n + 1);
+        if (k == 1) {
+            if (a[1] == 1)
+                printf("-1\n");
+            else
+                printf("0\n");
+            continue;
+        }
+        long long ans = 0;
+        int exp = 1;
+        for (int i = 1; i <= n && a[i] <= k; i++)
+            if (a[i] == k)
+                ans++, a[i]--;
+        bool flag = 0;
+        for (int i = 1; i <= n; i++) {
+            if (a[i] >= exp) {
+                ans += a[i] - exp, exp++;
+                if (exp == k) {
+                    printf("%lld\n", ans);
+                    flag = 1;
+                    break;
+                }
+            }
+        }
+        if (!flag) {
+            printf("-1\n");
+            continue;
+        }
+    }
+    return 0;
+}