Array Homework Question

Question

You are given an array with integers between 1 and 1,000,000. One integer is in the array twice. How can you determine which one? Can you think of a way to do it using littl

Answer 1

And how about the problem of finding ALL duplicates? Can this be done in less than O(n ln n) time? (Sort & scan) (If you want to restore the original array, carry along the original index and reorder after the end, which can be done in O(n) time)