1 files changed, 57 insertions, 0 deletions
diff --git a/works/solutions/acwing/2068.cpp b/works/solutions/acwing/2068.cpp
new file mode 100644
index 0000000..592f43f
--- /dev/null
+++ b/works/solutions/acwing/2068.cpp
@@ -0,0 +1,57 @@
+#include <algorithm>
+#include <cmath>
+#include <cstring>
+#include <iostream>
+
+int n, K;
+int A[100010];
+int c[11][100010];
+long long result;
+
+int CalcDigitCount(int n) {
+  int c = 0;
+  while (n != 0) {
+    c++;
+    n /= 10;
+  }
+  return c;
+}
+
+void work() {
+  for (int i = 0; i < n; i++) {
+    result += c[CalcDigitCount(A[i])][(K - A[i] % K) % K];
+    // Wrong Code I don't know why!
+    // int a = A[i];
+    // for (int j = 1; j < 11; j++) {
+    //   a *= 10;
+    //   a %= K;
+    //   c[j][a]++;
+    // }
+    for (int j = 0, power = 1; j < 11; j++) {
+      c[j][power * 1ll * A[i] % K]++;
+      power = power * 10 % K;
+    }
+  }
+}
+
+int main() {
+  std::ios_base::sync_with_stdio(false);
+  std::cin.tie(nullptr);
+
+  std::cin >> n >> K;
+
+  for (int i = 0; i < n; i++) {
+    std::cin >> A[i];
+  }
+
+  work();
+
+  std::reverse(A, A + n);
+  std::memset(c, 0, sizeof c);
+
+  work();
+
+  std::cout << result;
+
+  return 0;
+}