Cod sursa(job #936284)

Utilizator vld7Campeanu Vlad vld7 Data 6 aprilie 2013 15:30:10
Problema Arbori de intervale Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.44 kb
#include <fstream>
#include <algorithm>

using namespace std;

ifstream f("arbint.in");
ofstream g("arbint.out");

const int MAX_N = 100005;

int n, M, a[MAX_N], Aint[4 * MAX_N];

void build (int node, int left, int right) {
	if (left == right) {
		Aint[node] = a[left];
		return ;
	}
	
	int mid = (left + right) / 2;
	build (2 * node, left, mid);
	build (2 * node + 1, mid + 1, right);
	
	Aint[node] = max (Aint[2 * node], Aint[2 * node + 1]);
}

void update(int node, int left, int right, int pos, int val) {
	if (left == right) {
		Aint[node] = val;
		return ;
	}
	
	int mid = (left + right) / 2;
	if (pos <= mid)
		update (2 * node, left, mid, pos, val);
	else
		update (2 * node + 1, mid + 1, right, pos, val);
	
	Aint[node] = max (Aint[2 * node], Aint[2 * node + 1]);
}

int query(int node, int left, int right, int a, int b) {
	if (a <= left && right <= b)
		return Aint[node];
	
	int mid = (left + right) / 2;
	int result = 0;
	if (a <= mid)
		result = query (2 * node, left, mid, a, b);
	if (b > mid)
		result = max (result, query (2 * node + 1, mid + 1, right, a, b));
	
	return result;
}

int main() {
	f >> n >> M;
	for (int i = 1; i <= n; i++)
		f >> a[i];
	
	build (1, 1, n);
	
	for (int i = 1; i <= M; i++) {
		int op, a, b;
		
		f >> op >> a >> b;
		if (op == 0)
			g << query (1, 1, n, a, b) << '\n';
		else
			update (1, 1, n, a, b);
	}
	
	f.close();
	g.close();
	
	return 0;
}