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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].
解题思路:
不使用除法,返回一个数组,数组中第i个元素的值为nums[1]*..nums[i-1]*nums[i+1]…nums[n-1]。
利用前n个元素的乘积数组和后n个数组的乘积数组,得到结果。
暂时是能达到60ms
class Solution { public: vector<int> productExceptSelf(vector<int>& nums) { int n=nums.size(); vector<int>a=vector<int>(n,0); a[0]=1; for(int i=1;i<n;i++){ a[i]=a[i-1]*nums[i-1]; } for(int i=n-1;i>0;i--){ a[i-1]=a[i-1]*nums[i]; nums[i-1]=nums[i]*nums[i-1]; } //for(int i=0;i<n;i++)cout<<a[i]<<" "; return a; } }; |
238. Product of Array Except Self
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原文地址:http://www.cnblogs.com/olivelv/p/5226283.html