题目
Given an array of n integers where n > 1, nums
, return an array output
such that output[i]
is equal to the product of all the elements of nums
except nums[i]
.
Solve it without division and in O(n).
For example, given [1,2,3,4]
, return [24,12,8,6]
.
Follow up:
Could you solve it with constant space complexity? (Note: The output array does not count as extra space for the purpose of space complexity analysis.)
标签:Array
相似问题: (H) Trapping Rain Water, (M) Maximum Product Subarray, (H) Paint House II
题意
给定一个大小大于1的整型数组,返回一个数组,数组中每个元素的值为除了元素本身外所有元素的乘积。
解题思路
首先从左到右,每个数等于自己左边数的乘积,每个数再乘以自己右边的数,即为结果。
代码
public class Solution {
public int[] productExceptSelf(int[] nums) {
int length = nums.length;
int[] res = new int[length];
res[0] = 1;
for (int i = 1; i < length; i++) {
res[i] = res[i - 1] * nums[i - 1];
}
int tem = 1;
for (int i = length - 1; i >= 0; i--) {
res[i] = res[i] * tem;
tem = nums[i] * tem;
}
return res;
}
}