大整数乘法例子代码

/* 递归边界，如果是1位二进制数与1位二进制数相乘，则可以直接计算 */

/*累计做1位二进制乘法运算的次数*/

/* return (X*Y) */

/* 计算n的值 */

/* 把X和Y拆分开来，令X=A*2^(n/2)+B, 左移位运算，mod = 1<<(n/2) */

/* 计算XY=AC*2^n+(AD+CB)*2^(n/2)+BD */

/* 计算A*C，再向左移n位 */

/* 递归计算A*D */

/* 递归计算C*B */

/* 计算a21+a22,再向左移n/2位 */

/* 递归计算B*D */

/* XY=a1+a2+a3 */

-large integer multiplication example code / * Recursive border, if it is a binary number with a binary number multiplication, can be directly calculated * / / * the beginning of a binary multiplication of the number * / / * return (X * Y) * / / * calculate the value of n * / / * X and Y to split it so that X = A * 2 ^ (n / 2) B, the left shift operator, mod = 1LT; lt; (n / 2) * / / * calculate XY = AC * 2 ^ n (AD CB) * 2 ^ (n / 2) BD * / / * A * C calculation, further n-bits * / / * recursive computation A * D * / / * recursive calculation of C * B * / / * Calculation A21 A22 and then bits n / 2 * / / * recursive calculation B * D * / / * XY = a1 a2 a3 * /