如果WA 2 8 9 10,有可能是立方前缀和算错了, 13+23+33+.....+n3=((n+1)n/2)2 1^3+2^3+3^3+.....+n^3 = ({(n+1)n}/2)^213+23+33+.....+n3=((n+1)n/2)2