AtCoder/ABC077

atcoder/abc077/A/main.cpp

@@ -0,0 +1,17 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    string c1, c2;
+    cin >> c1 >> c2;
+    bool pass = (c1[0] == c2[2] && c2[0] == c1[2] && c1[1] == c2[1]);
+    cout << (pass ? "YES" : "NO") << endl;
+
+    return 0;
+}

atcoder/abc077/B/main.cpp

@@ -0,0 +1,17 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int N;
+    cin >> N;
+    int M = round(floor(sqrt(N)));
+    cout << (M * M) << endl;
+
+    return 0;
+}

atcoder/abc077/C/main.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int N;
+    cin >> N;
+
+    vector<int> A(N), B(N), C(N);
+    for (auto &a : A) cin >> a;
+    for (auto &b : B) cin >> b;
+    for (auto &c : C) cin >> c;
+    sort(A.begin(), A.end());
+    sort(B.begin(), B.end());
+    sort(C.begin(), C.end());
+
+    ll ans = 0;
+    for (int i = 0; i < N; ++i) {
+        auto ita = lower_bound(A.begin(), A.end(), B[i]);
+        int sa = distance(A.begin(), ita);
+        auto itb = upper_bound(C.begin(), C.end(), B[i]);
+        int sb = distance(itb, C.end());
+        ans += ll(sa) * sb;
+    }
+    cout << ans << endl;
+
+    return 0;
+}