boj 6549 히스토그램에서 가장 큰 직사각형

Author: emost22

세그먼트 트리2/6549.cpp

@@ -0,0 +1,68 @@
+#include <iostream>
+using namespace std;
+typedef long long ll;
+
+int list[100000], N;
+ll tree[400000];
+
+ll Max(ll x, ll y) {
+	return x > y ? x : y;
+}
+
+ll Min(ll x, ll y) {
+	return list[x] < list[y] ? x : y;
+}
+
+ll init(int node, int s, int e) {
+	if (s == e) {
+		return tree[node] = s;
+	}
+
+	int m = (s + e) / 2;
+	return tree[node] = Min(init(node * 2, s, m), init(node * 2 + 1, m + 1, e));
+}
+
+ll minindex(int node, int s, int e, int l, int r) {
+	if (e < l || s > r) return -1;
+	if (l <= s && e <= r) return tree[node];
+
+	int m = (s + e) / 2;
+	int m1 = minindex(node * 2, s, m, l, r);
+	int m2 = minindex(node * 2 + 1, m + 1, e, l, r);
+
+	if (m1 == -1) return m2;
+	else if (m2 == -1) return m1;
+	else {
+		return Min(m1, m2);
+	}
+}
+
+ll maxarea(int s, int e) {
+	int index = minindex(1, 0, N - 1, s, e);
+
+	ll area = (ll)(e - s + 1) *list[index];
+
+	if (s < index) area = Max(area, maxarea(s, index - 1));
+	if (index < e) area = Max(area, maxarea(index + 1, e));
+
+	return area;
+}
+
+int main() {
+	cin.tie(NULL); cout.tie(NULL);
+	ios::sync_with_stdio(false);
+
+	while (1) {
+		cin >> N;
+		if (!N) break;
+
+		for (int i = 0; i < N; i++) {
+			cin >> list[i];
+		}
+
+		init(1, 0, N - 1);
+		cout << maxarea(0, N - 1) << '\n';
+	}
+
+	return 0;
+}