git reimport

archive/2018.10/2018.10.29 - SNCK1B19/MAXPRODU.java

@@ -0,0 +1,54 @@
+package chelper;
+
+import java.util.Arrays;
+
+import io.InputReader;
+import io.OutputWriter;
+import misc.SimpleSavingChelperSolution;
+
+
+public class MAXPRODU extends SimpleSavingChelperSolution {
+
+  public static final long MOD = 1000000007;
+
+  public void solve(int testNumber, InputReader in, OutputWriter out) {
+    wrapSolve(testNumber, in, out);
+  }
+
+  @Override
+  public void solve(int testNumber) {
+    long n = in.nextLong();
+    long k = in.nextLong();
+
+    if (n < (1 + k) * k / 2) {
+      out.println(-1);
+      return;
+    }
+
+    long[] a = new long[(int) k];
+
+    long next = 1;
+    long left = n;
+    int i = 0;
+
+    while (i < k) {
+      long sum = (next + next + k - i - 1) * (k - i) / 2;
+      if (sum > left) {
+        left -= a[i];
+        i++;
+        continue;
+      }
+
+      a[i] = next;
+      next++;
+    }
+
+    long res = 1;
+    for (long j : a) {
+      res *= (j * j - j) % MOD;
+      res %= MOD;
+    }
+
+    out.println(res);
+  }
+}