public SegmentTree build(int start, int end) {
if (start > end) {
return null;
}
SegmentTree root = new SegmentTree(start, end);
if (start == end) {
return root;
}
int mid = start + ((end - start) >> 1);
root.left = build(start, mid);
root.right = build(mid + 1, end);
return root;
}
public void update(SegmentTree root, int p) {
if (root == null) {
return;
}
if (root.start == p && root.end == p) {
root.count++;
return;
}
int mid = root.start + ((root.end - root.start) >> 1);
if (mid >= p) {
update(root.left, p);
} else {
update(root.right, p);
}
root.count = 0;
if (root.left != null) {
root.count += root.left.count;
}
if (root.right != null) {
root.count += root.right.count;
}
}