Create quadtree.cpp

Changes

1 changed files (+34/-0)

• Data Structures/quadtree.cpp (new)
  • @@ -0,0 +1,34 @@
    + struct node { + int val; + node* c[4]; + node() { val = 0, c[0] = c[1] = c[2] = c[3] = 0; } + node* get_c(int i) { return (!c[i] ? c[i] = new node : c[i]); } + void update(int x, int y, int v, int xl = 0, int xh = 200005, int yl = 0, int yh = 200005) { + if (xl == xh && yl == yh) val = v; + else { + int xm = (xl + xh) / 2, ym = (yl + yh) / 2; + if (x <= xm) { + if (y <= ym) get_c(0)->update(x, y, v, xl, xm, yl, ym); + else get_c(1)->update(x, y, v, xl, xm, ym + 1, yh); + } + else { + if (y <= ym) get_c(2)->update(x, y, v, xm + 1, xh, yl, ym); + else get_c(3)->update(x, y, v, xm + 1, xh, ym + 1, yh); + } + val = max((c[0] ? c[0]->val : 0), val); + val = max((c[1] ? c[1]->val : 0), val); + val = max((c[2] ? c[2]->val : 0), val); + val = max((c[3] ? c[3]->val : 0), val); + } + } + int query(int xa, int xb, int ya, int yb, int xl = 0, int xh = 200005, int yl = 0, int yh = 200005) { + if (xl > xb || xh < xa || yl > yb || yh < ya) return 0; + if (xl >= xa && xh <= xb && yl >= ya && yh <= yb) return val; + int xm = (xl + xh) / 2, ym = (yl + yh) / 2, ret = 0; + ret = max((c[0] ? c[0]->query(xa, xb, ya, yb, xl, xm, yl, ym) : 0), ret); + ret = max((c[1] ? c[1]->query(xa, xb, ya, yb, xl, xm, ym + 1, yh) : 0), ret); + ret = max((c[2] ? c[2]->query(xa, xb, ya, yb, xm + 1, xh, yl, ym) : 0), ret); + ret = max((c[3] ? c[3]->query(xa, xb, ya, yb, xm + 1, xh, ym + 1, yh) : 0), ret); + return ret; + } + } root;