problem1 link 最优选择一定是在$2n$个端点中选出两个. problem2 link 分开考虑每个区间.设所有区间的左端点的最大值为$lc$,所有区间的右端点的最小值为$rc$.对于某个区间$L$,其实就是找最少的区间(包括$L$)能够完全覆盖区间$[lc,rc]$. 设$L$的左右端点为$L_{1},L_{2}$.考虑从$L_{1}$向左扩展,每次扩展一定是找一个区间$p$满足$p_{2}\geq L_{1}$且使得$p_{1}$最小.右端点向右扩展类似. problem3 li…
problem1 link 倒着想.每次添加一个右括号再添加一个左括号,直到还原.那么每次的右括号的选择范围为当前左括号后面的右括号减去后面已经使用的右括号. problem2 link 令$h(x)=\sum_{i=1}^{x}g(i)$,那么答案为$h(R)-h(L-1)$.对于$h(x)$: (1)如果$x\leq K$,那么$h(x)=0$ (2)否则对于$[K+1,x]$之间的所有偶数来说,对答案的贡献为$even+h(\frac{x}{2})-h(\frac{K}{2})$,其中$e…
Problem Statement You are given the ints perimeter and area. Your task is to find a triangle with the following properties: The coordinates of each vertex are integers between 0 and 3000, inclusive. The perimeter of the triangle must be exactly…
Problem Statement The Happy Letter game is played as follows: At the beginning, several players enter the field. Each player has a lowercase English letter on their back. The game is played in turns. In each turn, you select two players with dif…