[剑指offer]构建乘积数组

题目描述

给定一个数组A[0,1,...,n-1],请构建一个数组B[0,1,...,n-1],其中B中的元素B[i]=A[0]*A[1]*...*A[i-1]*A[i+1]*...*A[n-1]。不能使用除法。

 

 

 

题目链接：

https://www.nowcoder.com/practice/94a4d381a68b47b7a8bed86f2975db46?tpId=13&tqId=11204&rp=3&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

 

 

 

 

package com.sunshine.OFFER66_SECOND;

import org.junit.Test;

public class A51_multiply {

    @Test
    public void test() {
        int[] A = {1, 2, 3, 4};
        int[] multiply = multiply(A);
        for (int i : multiply) {
            System.out.println(i);
        }
    }

    public int[] multiply(int[] A) {
        int left = 1;
        int right = 1;
        int[] B = new int[A.length];
        for (int i = 0; i < B.length; i++) {
            B[i] = 1;
        }
        for (int i = 1; i < A.length; i++) {
            left *= A[i - 1];
            B[i] *= left;
        }
        for (int i = A.length - 2; i >= 0; i--) {
            right *= A[i + 1];
            B[i] *= right;
        }
        return B;
    }
}