文章目录lcaTarjan板子题:1172.祖孙询问lca或tarjan:1171.距离356.次小生成树352.闇の連鎖lcaO(mlogn)O(mlogn)O(mlogn),n为节点数量,m为询问次数,lca是一种在线处理询问的算法自己也是自己的祖先倍增:fa(i,j)fa(i,j)fa(i,j)表示从i开始,向上走2j2^j2j步走到的点j=0,走到父节点j>0,分两步走,先走到2j−12^{j-1}2j−1步再走2j−12^{j-1}2j−1步,那么一共就会走2j2^j2j步,fa(i,j)=fa(fa(i,j−1),j−1)fa(i,j)=fa(fa(i,j-1),j-1)fa(i,