Cod sursa(job #917402)

Utilizator apopeid13Apopeid Alejandro apopeid13 Data 17 martie 2013 20:25:05
Problema Arbori de intervale Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.69 kb
#include <iostream>
#include <fstream>
#include <vector>
 
using namespace std;
 
class SegmentTree {
  public:
    SegmentTree(const vector<int>& input) {
        size_ = 1;
        while (size_ < input.size())
            size_ *= 2;
        data_ = new int[size_ * 2];
 
        for (size_t i = 0; i < input.size(); ++i)
            data_[size_ + i] = input[i];
        for (size_t i = input.size(); i < size_; ++i)
            data_[size_ + i] = 0;
         
        for (size_t i = size_ - 1; i; --i)
            data_[i] = max(data_[i * 2], data_[i * 2 + 1]);
    }
 
    void update(int where, const int &value) {
        where += size_;
        data_[where] = value;
        for (where /= 2; where > 0; where /= 2)
            data_[where] = max(data_[where * 2], data_[where * 2 + 1]);
    }
 
    int query(int from, int to) {
        int answer = 0;
        from += size_;
        to += size_;
        while (from <= to) {
            answer = max(answer, data_[from]);
            from = (from + 1) / 2;
 
            answer = max(answer, data_[to]);
            to = (to - 1) / 2;
        }
 
        return answer;
    }
 
    ~SegmentTree() {
        delete[] data_;
    }
 
  private:
    size_t size_;
    int* data_;
};
 
int main() {
    ifstream cin("arbint.in");
    ofstream cout("arbint.out");
 
    int N, M; cin >> N >> M;
 
    vector<int> A(N);
    for (int i = 0; i < N; ++i)
        cin >> A[i];
 
    SegmentTree S(A);
    for (int i = 0; i < M; ++i) {
        int type, x, y; cin >> type >> x >> y;
        if (type == 0)
            cout << S.query(x - 1, y - 1) << "\n";
        else
            S.update(x - 1, y);
    }
}