2D segment tree

int m;
int tree[1505][1505], ara[505][505];

void build_y (int vx, int lx, int rx, int vy, int ly, int ry) {
    if (ly == ry)
        if (lx == rx)
            tree[vx][vy] = ara[lx][ly];
        else
            tree[vx][vy] = max(tree[vx*2][vy], tree[vx*2+1][vy]);
    else {
        int my = (ly + ry) / 2;
        build_y (vx, lx, rx, vy*2, ly, my);
        build_y (vx, lx, rx, vy*2+1, my+1, ry);
        tree[vx][vy] = max(tree[vx][vy*2], tree[vx][vy*2+1]);
    }
}

void build_x (int vx, int lx, int rx) {
    if (lx != rx) {
        int mx = (lx + rx) / 2;
        build_x (vx*2, lx, mx);
        build_x (vx*2+1, mx+1, rx);
    }
    build_y (vx, lx, rx, 1, 1, m);
}

void update_y (int vx, int lx, int rx, int vy, int ly, int ry, int x, int y, int new_val) {
    if (ly == ry) {
        if (lx == rx)
            tree[vx][vy] = new_val;
        else
            tree[vx][vy] = max(tree[vx*2][vy], tree[vx*2+1][vy]);
    }
    else {
        int my = (ly + ry) / 2;
        if (y <= my)
            update_y (vx, lx, rx, vy*2, ly, my, x, y, new_val);
        else
            update_y (vx, lx, rx, vy*2+1, my+1, ry, x, y, new_val);
        tree[vx][vy] = max(tree[vx][vy*2], tree[vx][vy*2+1]);
    }
}

void update_x (int vx, int lx, int rx, int x, int y, int new_val) {
    if (lx != rx) {
        int mx = (lx + rx) / 2;
        if (x <= mx)
            update_x (vx*2, lx, mx, x, y, new_val);
        else
            update_x (vx*2+1, mx+1, rx, x, y, new_val);
    }
    update_y (vx, lx, rx, 1, 1, m, x, y, new_val);
}

int get_y (int vx, int vy, int tly, int try_, int ly, int ry) {
    if (ly > ry)
        return 0;
    if (ly == tly && try_ == ry)
        return tree[vx][vy];
    int tmy = (tly + try_) / 2;
    return max(get_y (vx, vy*2, tly, tmy, ly, min(ry,tmy)), get_y (vx, vy*2+1, tmy+1, try_, max(ly,tmy+1), ry));
}

int get_x (int vx, int tlx, int trx, int lx, int rx, int ly, int ry) {
    if (lx > rx)
        return 0;
    if (lx == tlx && trx == rx)
        return get_y (vx, 1, 1, m, ly, ry);
    int tmx = (tlx + trx) / 2;
    return max(get_x (vx*2, tlx, tmx, lx, min(rx,tmx), ly, ry), get_x (vx*2+1, tmx+1, trx, max(lx,tmx+1), rx, ly, ry));
}