Merge pull request #1319 from AlgorithmWithGod/khj20006

[20251105] BOJ / P4 / 방어선 / 권혁준

Author: ShinHeeEul

khj20006/202511/05 BOJ P4 방어선.md

@@ -0,0 +1,60 @@
+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+
+int T, N;
+vector<int> seg, arr, cnt, cnt2;
+vector<pair<int, int>> arr2;
+
+void upt(int s, int e, int i, int v, int n) {
+	if (s == e) {
+		seg[n] = v;
+		return;
+	}
+	int m = (s + e) >> 1;
+	if (i <= m) upt(s, m, i, v, n << 1);
+	else upt(m + 1, e, i, v, n << 1 | 1);
+	seg[n] = max(seg[n << 1], seg[n << 1 | 1]);
+}
+
+int find(int s, int e, int l, int r, int n) {
+	if (l > r || l > e || r < s) return 0;
+	if (l <= s && e <= r) return seg[n];
+	int m = (s + e) >> 1;
+	return max(find(s, m, l, r, n << 1), find(m + 1, e, l, r, n << 1 | 1));
+}
+
+int main() {
+	cin.tie(0)->sync_with_stdio(0);
+
+	for (cin >> T; T--;) {
+		cin >> N;
+		seg = vector<int>(4 * N);
+		arr = vector<int>(N + 1);
+		cnt = vector<int>(N + 1);
+		cnt2 = vector<int>(N + 1);
+		arr2 = vector<pair<int, int>>();
+		for (int i = 1; i <= N; i++) {
+			cin >> arr[i];
+			arr2.emplace_back(arr[i], i);
+			cnt[i] = arr[i - 1] < arr[i] ? cnt[i - 1] + 1 : 1;
+		}
+		sort(arr2.begin(), arr2.end(), [](auto a, auto b) -> bool {
+			if (a.first == b.first) return a.second > b.second;
+			return a.first < b.first;
+		});
+
+		for (auto [x, i] : arr2) {
+			cnt2[i] = find(1, N, 1, i - 1, 1) + 1;
+			upt(1, N, i, cnt[i], 1);
+		}
+		int ans = 0;
+		for (int i = 1; i <= N; i++) {
+			if (arr[i - 1] < arr[i]) cnt2[i] = max(cnt2[i], cnt2[i - 1] + 1);
+			ans = max(ans, cnt2[i]);
+		}
+		cout << ans << '\n';
+	}
+
+}
+```