Create SegTree.cpp

Data Structures/SegTree.cpp

@@ -0,0 +1,40 @@
+struct Tree {
+	typedef int T;
+	static constexpr T unit = INT_MIN;
+	T f(T a, T b) { return max(a,b); } // any associative function
+	vector<T> s; int n;
+	Tree (int n = 0, T def = unit) : s(2*n, def), n(n) {}
+	void update(int pos, T val)
+	{
+		for(s[pos += n] = val; pos /= 2;)
+			s[pos] = f(s[pos*2], s[pos*2 + 1]);
+	}
+	T query(int b, int e) // query [b,e)
+	{
+		T ra = unit; T rb = unit;
+		for(b += n, e += n; b < e; b /= 2, e /= 2)
+		{
+			if(b%2) ra = f(ra, s[b++]);
+			if(e%2) rb = f(s[--e], rb);
+		}
+		return f(ra,rb);
+	}
+};
+
+void solve() {
+	int n;
+	cin >> n;
+	Tree st(n,0);
+	for(int i = 0; i < n; ++i)
+	{
+		int x; cin >> x;
+		st.update(i,x);
+	}
+	int m;
+	cin >> m;
+	for(int i = 0; i < m; ++i)
+	{
+		int l,r; cin >> l >> r;
+		cout << st.query(--l,r) << '\n';
+	}
+}