Codeforces Round #737 (Div. 2)
题号题目知识点AEzzat and Two Subsequences思维(略)BMoamen and k-subarrays思维(略)CMoamen and XOR二进制DEzzat and Grid线段树思维EAssiut Chess
Strange Memory Gym - 102832F
题意:
有一颗n个节点的树,求下面公式的值: 题解:
a ⊕ b c 可以推出a ⊕ c b 那么ai⊕ajalca(i,j)a_{lca(i,j)}alca(i,j),可以得到:ai⊕alca(i,j)a_{lca(i,j)}alca(i,j)aj,ai就…