Arithmetic Subarrays.cpp

/* Leet Code */
/* Title - Arithmetic Subarrays */
/* Created By - Akash Modak */
/* Date - 06/06/2023 */

// 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.
// Example 2:

// Input: nums = [-12,-9,-3,-12,-6,15,20,-25,-20,-15,-10], l = [0,1,6,4,8,7], r = [4,4,9,7,9,10]
// Output: [false,true,false,false,true,true]

class Solution {
public:
    vector<bool> checkArithmeticSubarrays(vector<int>& nums, vector<int>& l, vector<int>& r) {
        vector<bool> res;
        int start, end, cd, flag=0;
        for(int i=0;i<l.size();i++){
            start=l[i];
            end=r[i];
            if(end-start<2) {
                res.push_back(true);
                continue;
            }
            vector<int> v(nums.begin()+start,nums.begin()+end+1);
            cout<<v[v.size()-1]<<endl;
            sort(v.begin(),v.end());
            
            cd=v[1]-v[0];
            for(int j=1;j<v.size();j++){
                if(v[j]-v[j-1]!=cd) {
                    flag=1;
                    break;
                }
            }
            if(flag) res.push_back(false);
            else res.push_back(true);
            flag=0;
        }
        return res;
    }
};