[理工] [離散]字串的組合問題
Consider the collection of strings of length 10,
Ci E {0, 1, 2, 3} for all i = 1~10
How many of these strings have even weight?
(C1+C2+C3+...+C10 mod 2 = 0)
答案是 2^10[C(10,0)+C(10,2)+C(10,4)+...+C(10,10)]
不知道怎麼算出來的, 請幫個忙 @@?
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