Find the missing and duplicate elements in an array in linear time and constant space

Question

You’re given an array of N 64 bit integers. N may be very large. You know that every integer 1..N appears once in the array, except there is one integer mis

Answer 1

    long long int len = A.size();
    long long int sumOfN = (len * (len+1) ) /2, sumOfNsq = (len * (len +1) *(2*len +1) )/6;
    long long int missingNumber1=0, missingNumber2=0;

    for(int i=0;i