摘要:
**全错排:**n封信放入n个信封,要求全部放错,共有多少种放法,记n个元素的错排总数为f(n)方法一: 某人写了n封信和n个信封,如果所有的信都装错了信封。求所有的信都装错信封,共有多少种不同情况。 当N=1和2时,易得解~,假设F(N-1)和F(N-2)已经得到,重点分... 阅读全文
摘要:
RXD and dividing题目链接Problem Description RXD has a tree T, with the size of n. Each edge has a cost. Define f(S) as the the cost of the minimal... 阅读全文
摘要:
Kanade’s sumTime Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 2553 Accepted Submissi... 阅读全文