Add 01086.cpp

01xxx/01086.cpp

@@ -0,0 +1,56 @@
+#include <iostream>
+#include <string>
+#include <vector>
+using namespace std;
+
+long long gcd(long long a, long long b) {
+  return b ? gcd(b, a % b) : a;
+}
+
+void solve(void) {
+  int n; cin >> n;
+  vector<string> s(n);
+  for (int i=0; i<n; i++) cin >> s[i];
+  int k; cin >> k;
+
+  vector<int> a(n, 0);
+  for (int i=0; i<n; i++) {
+    for (char c : s[i]) {
+      a[i] = (10 * a[i] + c - '0') % k;
+    }
+  }
+
+  vector<int> ten(55, 1 % k);
+  for (int i=1; i<55; i++) {
+    ten[i] = (10 * ten[i-1]) % k;
+  }
+
+  vector<vector<long long>> dp(1<<n, vector<long long>(k, 0));
+  dp[0][0] = 1;
+  for (int mask=0; mask<(1<<n); mask++) {
+    for (int i=0; i<n; i++) {
+      if (mask & (1<<i)) continue;
+      for (int j=0; j<k; j++) {
+        dp[mask | (1<<i)][(j * ten[s[i].size()] + a[i]) % k] += dp[mask][j];
+      }
+    }
+  }
+
+  if (!dp[(1<<n)-1][0]) {
+    cout << "0/1";
+    return;
+  }
+
+  long long num = dp[(1<<n)-1][0], den = 1;
+  for (int i=1; i<=n; i++) den *= i;
+  long long g = gcd(num, den);
+  cout << num / g << "/" << den / g;
+}
+
+int main(void) {
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr);
+
+  solve();
+  return 0;
+}