problem1 link 遍历未被删除的叶子结点即可. problem2 link 首先,将所有的蛋白质原子编号,设为$[0,m-1]$,每个原子可能对应多个长度为3的$ACGT$.设$n$为DNA串的长度.用$g[i][j]$表示从$i$开始匹配数字$j$后的最小位置,$0\leq i \leq n-1,0\leq j \leq m-1$. 然后就是动态规划.设$dp[i][j]$表示位置$i$之前最后匹配的数字为$j$的方案数.对所有的$0\leq t < m$有$dp[g[i][t]][…
problem1 link 倒着想.每次添加一个右括号再添加一个左括号,直到还原.那么每次的右括号的选择范围为当前左括号后面的右括号减去后面已经使用的右括号. problem2 link 令$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…
