ProductofArrayExceptSelf.cpp

// Product of Array Except Self

// Source - LEETCODE

// 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]


class Solution {
public:
    vector<int> productExceptSelf(vector<int>& nums) {
        vector<int> posofzeros;
        vector<int> res(nums.size(), 0);
        for(int i = 0; i < nums.size(); i++){
            if(nums[i] == 0){
                posofzeros.push_back(i);
            }
        }
        int prod = 1;
        if(posofzeros.size() == 0){
            for(int i = 0; i < nums.size(); i++){
                prod*=nums[i];
            }
            for(int i = 0; i < nums.size(); i++){
                res[i] = prod/nums[i];
            }
            return res;
        }
        if(posofzeros.size() == 1){
            for(int i = 0; i < nums.size(); i++){
                if(posofzeros[0] != i){
                    prod*=nums[i];
                }
            }
            res[posofzeros[0]] = prod;
            return res;
        }
        else{
            return res;
        }
    }
};