[算法设计]分治思想实例——大整数乘法(Java实现)

//Java代码实现
public static long multip(long x,long y,int n) {
        if(1 == n) {
            return x*y;
        }
        else {
            long nx1 = (long) (x/Math.pow(10,n/2));
            long nx2 = x - nx1 * (long) (Math.pow(10,n/2));
            long ny1 = (long) (y/Math.pow(10,n/2));
            long ny2 = y - ny1 * (long) (Math.pow(10,n/2));
            
            long nx1y1 = multip(nx1,ny1,n/2);
            long nx2y2 = multip(nx2,ny2,n/2);
            
            long nx1y2x2y1 = multip(nx1 - nx2,ny2 - ny1,n/2) + nx1y1 + nx2y2;
            
            return nx1y1 * (long)Math.pow(10, n) + nx1y2x2y1 * (long)Math.pow(10,n/2) + nx2y2;
            }
    }
    

（总结自网易云课堂《算法设计与分析之入门篇》）