Method mk

code/data-structures/segment_tree.cpp:8–12

  segment_tree(const vector<ll> &a) : n(size(a)), arr(4*n) {
    mk(a,0,0,n-1); }
  node mk(const vector<ll> &a, int i, int l, int r) {
    int m = (l+r)/2;
    return arr[i] = l > r ? node(l,r) :
      l == r ? node(l,r,a[l]) :
      node(mk(a,2*i+1,l,m),mk(a,2*i+2,m+1,r)); }
  node update(int at, ll v, int i=0) {
    propagate(i);
    int hl = arr[i].l, hr = arr[i].r;