simplify loop
add comment
optimise bfs and comment
double links_ovs
simplify getChild with double links_ovs
排序和父子关系确定 done
add testcase of sort when ovs empty
calculate x and with sorted seq
计算坐标成功，Plot 中父序列获取有bug
plot 中先 sort 后计算坐标主流程完成
layout optimise