摘要:
题意:给一个1-n的排列, 你需要求出有多少个区间满足a[l] + a[r] = max(a[l] - a[r]); 解题思路 首先记录每个数字的下标 然后用单调栈维护以 a[i] 为最高点的区间 然后枚举 a[i] 区间内较短一侧的数 因为1 - n 排列数值唯一且已经记录了位置, 所以可以 O( 阅读全文
摘要:
You are given a tree (an undirected connected acyclic graph) consisting of nn vertices and n−1n−1 edges. A number is written on each edge, each number 阅读全文