ADATREE.cpp

// Ivan Carvalho
// Solution to https://www.spoj.com/problems/ADATREE/
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 3 * 1e5 + 10;
typedef tuple<int, int, int, int> quadra;
typedef pair<int, int> ii;
vector<ii> atualizacoes;
vector<quadra> queries;
int n, m, ptr, resp[MAXN], seg[4 * MAXN];
void update(int pos, int left, int right, int x, int val) {
    if (left == right) {
        seg[pos] = val;
        return;
    }
    int mid = (left + right) / 2;
    seg[pos] = max(seg[pos], val);
    if (x <= mid) {
        update(2 * pos + 1, left, mid, x, val);
    } else {
        update(2 * pos + 2, mid + 1, right, x, val);
    }
}
int query(int pos, int left, int right, int i, int j) {
    if (left >= i && right <= j) {
        return seg[pos];
    }
    int mid = (left + right) / 2;
    if (j <= mid) {
        return query(2 * pos + 1, left, mid, i, j);
    } else if (i >= mid + 1) {
        return query(2 * pos + 2, mid + 1, right, i, j);
    } else {
        return max(query(2 * pos + 1, left, mid, i, j),
                   query(2 * pos + 2, mid + 1, right, i, j));
    }
}
int main() {
    scanf("%d %d", &n, &m);
    for (int i = 0; i < n; i++) {
        int x;
        scanf("%d", &x);
        atualizacoes.push_back(ii(x, i));
    }
    sort(atualizacoes.begin(), atualizacoes.end());
    for (int i = 0; i < m; i++) {
        int a, b, c;
        scanf("%d %d %d", &a, &b, &c);
        queries.push_back(make_tuple(c, a, b, i));
    }
    sort(queries.begin(), queries.end());
    for (int i = 0; i < m; i++) {
        int h = get<0>(queries[i]), a = get<1>(queries[i]),
            b = get<2>(queries[i]), idx = get<3>(queries[i]);
        while (ptr < n && atualizacoes[ptr].first <= h) {
            update(0, 0, n - 1, atualizacoes[ptr].second,
                   atualizacoes[ptr].first);
            ptr++;
        }
        resp[idx] = query(0, 0, n - 1, a, b);
    }
    for (int i = 0; i < m; i++) printf("%d\n", resp[i]);
    return 0;
}