2020-2021:teams:legal_string:组队训练比赛记录:contest17
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2020-2021:teams:legal_string:组队训练比赛记录:contest17 [2021/09/01 09:19] jxm2001 [题解] |
2020-2021:teams:legal_string:组队训练比赛记录:contest17 [2021/09/05 10:20] (当前版本) jxm2001 [题意] |
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|---|---|---|---|
| 行 6: | 行 6: | ||
| | C | 0 | 0 | 0 | | | C | 0 | 0 | 0 | | ||
| | D | 0 | 0 | 0 | | | D | 0 | 0 | 0 | | ||
| - | | E | 2 | 0 | 0 | | + | | E | 2 | 2 | 0 | |
| | H | 2 | 0 | 0 | | | H | 2 | 0 | 0 | | ||
| | J | 2 | 0 | 0 | | | J | 2 | 0 | 0 | | ||
| 行 18: | 行 18: | ||
| $$ | $$ | ||
| - | \sum_{i=1}^n\sum_{j=1}^n {i+j\choose j}f(i,j)\\ | + | \sum_{i=1}^n\sum_{j=1}^n {i+j\choose j}f(i+j,i)\\ |
| f(i,j)= | f(i,j)= | ||
| \begin{cases} | \begin{cases} | ||
| 行 49: | 行 49: | ||
| S(i+1)&=\sum_{j=1}^n {i+j+1\choose j}A^iB^j \\ | S(i+1)&=\sum_{j=1}^n {i+j+1\choose j}A^iB^j \\ | ||
| &=\sum_{j=1}^n \left({i+j\choose j}+{i+j\choose j-1}\right)A^iB^j\\ | &=\sum_{j=1}^n \left({i+j\choose j}+{i+j\choose j-1}\right)A^iB^j\\ | ||
| - | &=AS(i)+\sum_{j=0}^{n-1}{i+j+1\choose j}A^{i-1}B^jB\\ | + | &=AS(i)+\sum_{j=0}^{n-1}{i+j+1\choose j}A^{i}B^jB\\ |
| & =AS(i)+\left(S(i+1)+A^i-{i+n+1\choose i+1}A^iB^n\right)B | & =AS(i)+\left(S(i+1)+A^i-{i+n+1\choose i+1}A^iB^n\right)B | ||
| \end{split}\end{equation} | \end{split}\end{equation} | ||
2020-2021/teams/legal_string/组队训练比赛记录/contest17.1630459150.txt.gz · 最后更改: 2021/09/01 09:19 由 jxm2001
