编写利用分治法求解大整数乘法的java函数
时间: 2024-05-08 15:18:46 浏览: 159
我可以回答这个问题。以下是一个利用分治法求解大整数乘法的Java函数的示例代码:
```
import java.math.BigInteger;
public class BigMultiplication {
public static BigInteger multiplication(BigInteger x, BigInteger y) {
int maxLength = Math.max(x.bitLength(), y.bitLength());
if (maxLength <= 2000) {
return x.multiply(y); // 直接使用内置函数实现大整数乘法
}
maxLength = (maxLength / 2) + (maxLength % 2);
BigInteger xl = x.shiftRight(maxLength);
BigInteger xr = x.subtract(xl.shiftLeft(maxLength));
BigInteger yl = y.shiftRight(maxLength);
BigInteger yr = y.subtract(yl.shiftLeft(maxLength));
BigInteger p1 = multiplication(xl, yl);
BigInteger p2 = multiplication(xr, yr);
BigInteger p3 = multiplication(xl.add(xr), yl.add(yr));
return p1.shiftLeft(maxLength * 2).add(p3.subtract(p1).subtract(p2).shiftLeft(maxLength)).add(p2);
}
public static void main(String[] args) {
BigInteger x = new BigInteger("3141592653589793238462643383279502884197169399375105820974944592");
BigInteger y = new BigInteger("2718281828459045235360287471352662497757247093699959574966967627");
BigInteger result = multiplication(x, y);
System.out.println(result);
}
}
```
此函数利用分治法将大整数乘法拆分成多个小问题解决,最终合并计算结果。当数位较少时,直接使用Java内置函数实现;当数位较多时,采用分治法加速计算。
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