[剑指Offer][数组]构建乘积数组

 1 public class Solution {
 2     public int[] multiply(int[] array) {
 3         if(array.length <= 1) {
 4             return new int[0];
 5         }
 6         int[] result = new int[array.length];
 7         for(int i = 0; i < array.length; i ++) {
 8             result[i] = 1;
 9             for(int j = 0; j < array.length; j ++) {
10                 if(j == i) {
11                     continue;
12                 }
13                 result[i] = result[i] * array[j];
14                 if(result[i] == 0) {
15                     break;
16                 }
17             }
18         }
19         return result;
20     }
21 }

 1 public class Solution {
 2     public int[] multiply(int[] array) {
 3         if(array.length <= 1) {
 4             return new int[0];
 5         }
 6         int[] result = new int[array.length];
 7         int[] left = new int[array.length];
 8         int[] right = new int[array.length];
 9         left[0] = 1;
10         right[array.length - 1] = 1;
11         for(int i = 1; i < array.length; i ++) {
12             left[i] = left[i - 1] * array[i - 1];
13         }
14         for(int j = array.length - 2; j >= 0; j --) {
15             right[j] = right[j + 1] * array[j + 1];
16         }
17         for(int m = 0; m < array.length; m ++) {
18             result[m] = left[m] * right[m];
19         }
20         return result;
21     }
22 }