https://www.wolframalpha.com/input/?i=Max%5BTable%5B%28ab%2Bc%2822-a-b-c%29%29Boole%5Ba%2Bb%2Bc%3C22%5D%2C+%7Ba%2C+19%7D%2C+%7Bb%2C+19%7D%2C+%7Bc%2C+19%7D%5D%5D

证明的话，(a+b+c+d)^2 = 4(ab+cd) + (a-b)^2 + (c-d)^2 + 2(a+b)(c+d), 所以a=floor(n/2-1),b=ceiling(n/2-1),c=d=1; n=a+b+c+d

锟斤拷锟洁辑时锟斤拷: 2021-04-20 23:17:29