Leetcode 238_leetcode238

1. Product of Array Except Self
   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].

class Solution {
public:
    vector<int> productExceptSelf(vector<int>& nums) {
        vector <int >answer1;
        vector <int >answer;
        int temp=1;
        for(int i=0;i<nums.size();++i){

            if(i==0){
                temp=nums[i];
            }
            else{

                answer1.push_back(temp);
                temp*=nums[i];
            }
        }

        for(int i=nums.size()-1;i>=0;--i){

            if(i==nums.size()-1){
                answer.push_back(answer1[i-1]);
                temp=nums[i];
            }
            else if(i==0){
                answer.push_back(temp);
            }
            else{

                answer.push_back(temp*answer1[i-1]);
                temp*=nums[i];

            }
        }
        int i=0,j=answer.size()-1;
        while(i<j){
            swap(answer[i++],answer[j--]);

        }
        return answer;
    }
};
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