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two pointer technique which is used to solve some basic algorithms related question like 2sum, 3sum, and difference of 2 item in a vector equal to given target

the two-pointer technique is a very popular technique to solve some basic problem like

just watch this nice video for more information

https://www.youtube.com/watch?v=2wVjt3yhGwg&t=174s

https://leetcode.com/articles/two-pointer-technique/

1. Given a vector of integers and a target sum returns true if any two elements sum is equal to the target in the given vector

bool checkSum(int sum, vector<int> &myVect)

{

    sort(myVect.begin(),myVect.end());

    int i=0,j=myVect.size()-1;

    while(j>=i)

    {

        if(myVect[i]+myVect[j]==sum)

        {

            return true;

        }else if(myVect[i]+myVect[j]>sum)

        {

            j--;

        }else if(myVect[j]+myVect[i]<sum)

        {

            i++;

        }

    }

    return false;

}

2. Given a vector of integers and a target difference returns true if any two elements dfference in vector is equal to the target in the given vector.


bool checkDiff(int dif,vector<int> &myVect)

{

    sort(myVect.begin(),myVect.end());

    int i=0;

    int j=1;

    int size=myVect.size()-1;

    while(i<=size && j<=size)

    {

    

        if(myVect[j]-myVect[i]==dif)

        {

            return true;

        }else if(myVect[j]-myVect[i]<dif)

        {

            j++;

        }else if(myVect[j]-myVect[i]>dif)

        {

            i++;

        }

        

    }

    return false;

}

working sample 

https://www.onlinegdb.com/edit/HJooqlZLP



 


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