Arithmetic_Subarrays.cpp

PROBLEM STATEMENT :- 
  A sequence of numbers is called arithmetic if it consists of at least two elements, and the difference between every two consecutive elements is the same. 
  More formally, a sequence s is arithmetic if and only if s[i+1] - s[i] == s[1] - s[0] for all valid i.

For example, these are arithmetic sequences:

1, 3, 5, 7, 9
7, 7, 7, 7
3, -1, -5, -9
The following sequence is not arithmetic:

1, 1, 2, 5, 7
You are given an array of n integers, nums, and two arrays of m integers each, l and r, representing the m range queries, where the ith query is the range [l[i], r[i]]. 
All the arrays are 0-indexed.

Return a list of boolean elements answer, where answer[i] is true if the subarray nums[l[i]], nums[l[i]+1], ... , nums[r[i]] can be rearranged to form an arithmetic sequence,
and false otherwise.
  
  
  Example 1:

Input: nums = [4,6,5,9,3,7], l = [0,0,2], r = [2,3,5]
Output: [true,false,true]
Explanation:
In the 0th query, the subarray is [4,6,5]. This can be rearranged as [6,5,4], which is an arithmetic sequence.
In the 1st query, the subarray is [4,6,5,9]. This cannot be rearranged as an arithmetic sequence.
In the 2nd query, the subarray is [5,9,3,7]. This can be rearranged as [3,5,7,9], which is an arithmetic sequence.
  
  SOLUTION :-
    class Solution {
public:
    vector<bool> checkArithmeticSubarrays(vector<int>& nums, vector<int>& l, vector<int>& r)
    {
         vector<bool> res;
        for(int i=0;i<l.size();i++)
        {
            vector<int> ans;
            for(int w=l[i];w<=r[i] ;w++)
            {
                ans.push_back(nums[w]);
            }
            sort(ans.begin(),ans.end());
            if(ans.size()==1)
                res.push_back(true);
            else
            {
                int k=ans[1]-ans[0];
                bool f=true;
                for(int p=2;p<ans.size();p++)
                {
                    int diff=ans[p]-ans[p-1];
                    if(diff!=k)
                    {
                        res.push_back(false);
                        f=false;
                        break;
                    }
                }
                if(f==true)
                    res.push_back(true);
            }
        }
        return res;
    }
};