Cod sursa(job #1109512)

Utilizator a_h1926Heidelbacher Andrei a_h1926 Data 17 februarie 2014 11:39:36
Problema Arbori de intervale Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.82 kb
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

class SegmentTree {
  public:
    static const int oo = 0x3f3f3f3f;

    SegmentTree(const vector<int> &values):
      size(1),
      tree(vector<int>()) {
        for (; size < int(values.size()); size *= 2);
        tree = vector<int>(2 * size, -oo);
        for (int x = 0; x < int(values.size()); ++x)
            tree[size + x] = values[x];
        for (int x = size - 1; x > 0; --x)
            tree[x] = max(tree[2 * x], tree[2 * x + 1]);
    }

    void Update(int where, const int value) {
        tree[where += size] = value;
        for (where /= 2; where > 0; where /= 2)
            tree[where] = max(tree[2 * where], tree[2 * where + 1]);
    }

    int Query(int from, int to) const {
        int answer = -oo;
        from += size;
        to += size;
        while (from <= to) {
            answer = max(answer, max(tree[from], tree[to]));
            from = (from + 1) / 2;
            to = (to - 1) / 2;
        }
        return answer;
    }

  private:
    int size;
    vector<int> tree;
};

int main() {
    ifstream cin("arbint.in");
    ofstream cout("arbint.out");
    int n, q;
    cin >> n >> q;
    vector<int> values = vector<int>(n);
    for (int i = 0; i < n; ++i)
        cin >> values[i];
    SegmentTree tree = SegmentTree(values);
    for (; q > 0; --q) {
        int type;
        cin >> type;
        if (type == 0) {
            int from, to;
            cin >> from >> to;
            --from;
            --to;
            cout << tree.Query(from, to) << "\n";
        } else {
            int where, value;
            cin >> where >> value;
            --where;
            tree.Update(where, value);
        }
    }
    cin.close();
    cout.close();
    return 0;
}