高精度大整数乘法,对于大整数比较方便的输入方法是，按字符型处理，两个成熟存储在字符串数组s1，s2中，计算结果存储在整型数组a中。-Precision large integer multiplication, more convenient for large integer input method is handled by the character, two mature stored in an array of strings s1, s2, the calculation result is stored in an integer array a.