Find The Missing Duplicate in a Given Array.

Objec­tive: Given an Integer array. Array contains duplicates of all the numbers in array except one number . Find that number.

Example :

int [] A = { 2,1,3,5,5,3,2,1,6,7,7,8,8};
Output : Missing duplicate is 6


  • Naive solution is use Hash Table complexity – O(n)
  • Better solution – XOR
  • A^A = 0 and A^B^A = B, so if we XOR all the elements, the answer will be the missing no
  • If we have only one element, the missing no will be that no



Missing duplicate is 6

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