对于第一个for循环第一步：b[0] = 1;第二步：b[1] = b[0] * a[0] = a[0]第三步：b[2] = b[1] * a[1] = a[0] * a[1];第四步：b[3] = b[2] * a[2] = a[0] * a[1] * a[2];第五步：b[4] = b[3] * a[3] = a[0] * a[1] * a[2] * a[3];然后对于第二个for循环第一步temp *= a[4] = a[4]; b[3] = b[3] * temp = a[0] * a[1] * a[2] * a[4];第二步temp *= a[3] = a[4] * a[3];b[2] = b[2] * temp = a[0] * a[1] * a[4] * a[3];第三步temp *= a[2] = a[4] * a[3] * a[2]; b[1] = b[1] * temp = a[0] * a[4] * a[3] * a[2];第四步temp *= a[1] = a[4] * a[3] * a[2] * a[1]; b[0] = b[0] * temp = a[4] * a[3] * a[2] * a[1];由此可以看出从b[4]到b[0]均已经得到正确计算。原文：https://www.cnblogs.com/MarkLeeBYR/p/9773723.html