P2782 友好城市

R72299495

Luogu/P2782/P2782.cpp

@@ -0,0 +1,33 @@
+#include <algorithm>
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e5 + 5;
+
+int n, f[N], ans;
+std::pair<int, int> a[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i].first >> a[i].second;
+    }
+
+    std::sort(a + 1, a + n + 1);
+
+    f[++ans] = a[1].second;
+    for (int i = 2; i <= n; i++) {
+        int k = std::upper_bound(f + 1, f + ans + 1, a[i].second) - f;
+        f[k] = a[i].second;
+        if (k > ans) ans++;
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}