例如:
A[]={1,2,3}求B[]
B[0]=A[1]×A[2]=2×3=6
B[1]=A[0]×A[2]=1×3=3
B[2]=A[0]×A[1]=1×2=2
所以 B 数组为{6,3,2}
import java.util.Arrays; public class Test52 { public static double[] multiply(double[] data) { if (data == null || data.length < 2) { return null; } double[] result = new double[data.length]; // result[0]取1 result[0] = 1; for (int i = 1; i < data.length; i++) { // 第一步每个result[i]都等于于data[0]*data[1]...data[i-1] // 当i=n-1时,此时result[n-1]的结果已经计算出来了【A】 result[i] = result[i -1] * data[i - 1]; } // tmp保存data[n-1]*data[n-2]...data[i+1]的结果 double tmp = 1; // 第二步求data[n-1]*data[n-2]...data[i+1] // 【A】result[n-1]的结果已经计算出来,所以从data.length-2开始操作 for (int i = data.length - 2; i >= 0; i--) { tmp *= data[i + 1]; result[i] *= tmp; } return result; } public static void main(String[] args) { double[] array1 = {1, 2, 3, 4, 5}; System.out.println(Arrays.toString(multiply(array1))); // double expected[] = {120, 60, 40, 30, 24}; double[] array2 = {1, 2, 0, 4, 5}; System.out.println(Arrays.toString(multiply(array2))); // double expected[] = {0, 0, 40, 0, 0}; double[] array3 = {1, 2, 0, 4, 0}; System.out.println(Arrays.toString(multiply(array3))); // double expected[] = {0, 0, 0, 0, 0}; double[] array4 = {1, -2, 3, -4, 5}; System.out.println(Arrays.toString(multiply(array4))); // double expected[] = {120, -60, 40, -30, 24}; double[] array5 = {1, -2}; System.out.println(Arrays.toString(multiply(array5))); // double expected[] = {-2, 1}; } }