Sdywolf的博客

DescriptionOne tradition of ACM-ICPC contests is that a team gets a balloon for every solved problem. We assume that the submission time doesn’t matter and teams are sorted only by the number of balloo

DescriptionYou are given a permutation of numbers from 1 to n. Determine whether there’s a pair of integers a, b (1 ≤ a, b ≤ n; a ≠ b) such that the element (note, that it is usual division, not integ

题意给n个数，问能否构造出一个相邻节点不互质的二叉搜索树。题解JZ太神了，看了一眼就说区间DP。定义lft[i][j]lft[i][j]lft[i][j]表示[i,j][i,j][i,j]接在i−1i−1i-1的右儿子是否可行，rgt[i][j]rgt[i][j]rgt[i][j]表示[i,j][i,j][i,j]接在j+1j+1j+1的左儿子是否可行。转移就用经典区间DP，枚...

题意给出一个[1,n][1,n][1,n]的排列，每次交换两个数，每次询问一个每一位都与这个数列不同排列，这样的排列的最大权值，一个排列的权值定义为a[i]∗b[p[i]]a[i]∗b[p[i]]a[i]*b[p[i]]。题解如果没有限制，由排序不等式，显然当aaa，bbb都顺序排列是最优解，现在有限制以后，可以证明（其实我不会）：每一位最多与排序后与它相差2的数配对。这样就可...