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# 題目敘述
Given an integer array nums , return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i] .
The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.
You must write an algorithm that runs in O(n) time and without using the division operation.
# Example 1
Input: nums = [1,2,3,4]
Output: [24,12,8,6]
# Example 2
Input: nums = [-1,1,0,-3,3]
Output: [0,0,9,0,0]
# 解題思路
# Solution
class Solution { | |
public int[] productExceptSelf(int[] nums) { | |
int n = nums.length; | |
int[] prefixSum = new int[n]; | |
int[] suffixSum = new int[n]; | |
int[] res = new int[n]; | |
prefixSum[0] = 1; | |
suffixSum[n - 1] = 1; | |
for(int i = 0; i < n - 1; i++){ | |
prefixSum[i + 1] = prefixSum[i] * nums[i]; | |
suffixSum[n - i - 2] = suffixSum[n - i - 1] * nums[n - i - 1]; | |
} | |
for(int i = 0; i < n; i++){ | |
res[i] = prefixSum[i] * suffixSum[i]; | |
} | |
return res; | |
} | |
} |
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