Add 27108.cpp

27xxx/27108.cpp

@@ -0,0 +1,37 @@
+#include <algorithm>
+#include <iostream>
+#include <utility>
+#include <vector>
+using namespace std;
+
+int gcd(int a, int b) {
+  return b ? gcd(b, a % b) : a;
+}
+
+bool cmp(const pair<int, int> &a, const pair<int, int> &b) {
+  return a.first * b.second < a.second * b.first;
+}
+
+void solve(void) {
+  int n; cin >> n;
+  vector<pair<int, int>> v;
+  for (int i=1; i<=n; i++) for (int j=0; j<=i; j++) {
+    int g = gcd(i, j);
+    v.push_back({j / g, i / g});
+  }
+  sort(v.begin(), v.end(), cmp);
+  v.erase(unique(v.begin(), v.end()), v.end());
+
+  cout << v.size() << "\n";
+  for (auto &p : v) {
+    cout << p.first << "/" << p.second << "\n";
+  }
+}
+
+int main(void) {
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr);
+
+  solve();
+  return 0;
+}