Lazy Segment Tree

#include <cstdio>
#include <algorithm>

#define MID ((l + r) / 2)

const int N(1 << 20)
const int INF(1e9)
const int UNDEF(-1)

using namespace std;
typedef pair<int,int> II;

struct SegmentTree{
    II T[N];
    int a, b, v;

    inline bool intersect(int l, int r){
        return max(l, a) <= min(r, b);
    }

    inline void clearlazy(int node, int l, int r){
        if(T[node].first == UNDEF) return;
        T[2 * node] = T[node];
        T[2 * node + 1] = T[node];
        T[node].first = UNDEF;
    }

    void uu(int node, int l, int r){
        if(a <= l and r <= b){
            T[node] = II(v, v);
            return;
        }
        if(not intersect(l, r)) return;
        clearlazy(node, l, r);
        uu(2 * node, l, MID);
        uu(2 * node + 1, MID + 1, r);
        T[node].second = max(T[2 * node].second, T[2 * node + 1].second);
    }

    int qq(int node, int l, int r){
        if(a <= l and r <= b) return T[node].second;
        if(not intersect(l, r)) return -INF;
        clearlazy(node, l, r);
        return max(qq(2 * node, l, MID), qq(2 * node + 1, MID + 1, r));
    }

    int query(int aa, int bb){
        a = aa;
        b = bb;
        return qq(1, 1, M.size());
    }

    void update(int aa, int bb, int val){
        a = aa;
        b = bb;
        v = val;
        uu(1, 1, M.size());
    }
};

/*
Lazy Segment Tree
update: set value in [l,r] to v
query:  find RMQ in [l,r]
*/