Add 01863.cpp

01xxx/01863.cpp

@@ -0,0 +1,32 @@
+#include <algorithm>
+#include <iostream>
+#include <stack>
+#include <vector>
+using namespace std;
+
+void solve(void) {
+  int n; cin >> n;
+  vector<pair<int, int>> v(n);
+  for (int i=0; i<n; i++) cin >> v[i].first >> v[i].second;
+  sort(v.begin(), v.end());
+
+  int ans = 0;
+  stack<int> s;
+  s.push(0);
+  for (int i=0; i<n; i++) {
+    if (s.top() < v[i].second) ans++, s.push(v[i].second);
+    else {
+      while (!s.empty() && s.top() > v[i].second) s.pop();
+      if (s.top() < v[i].second) ans++, s.push(v[i].second);
+    }
+  }
+  cout << ans;
+}
+
+int main(void) {
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr);
+
+  solve();
+  return 0;
+}