Two Sum


Java Algorithmic thinking Searching Public

Easy  

30min


Write a function that, given a list and a target sum, returns zero-based indices of any two distinct elements whose sum is equal to the target sum. If there are no such elements, the function should return null.

For example, findTwoSum(new int[] { 1, 3, 5, 7, 9 }, 12) should return a single dimensional array with two elements and contain any of the following pairs of indices:

  • 1 and 4 (3 + 9 = 12)
  • 2 and 3 (5 + 7 = 12)
  • 3 and 2 (7 + 5 = 12)
  • 4 and 1 (9 + 3 = 12)
Java SE 8
   

  •   Example case: java.lang.UnsupportedOperationException at TwoSum.findTwoSum(TwoSum.java:3)
  •   No solution: java.lang.UnsupportedOperationException at TwoSum.findTwoSum(TwoSum.java:3)
  •   One solution: java.lang.UnsupportedOperationException at TwoSum.findTwoSum(TwoSum.java:3)
  •   Performance test with a large number of elements: java.lang.UnsupportedOperationException at TwoSum.findTwoSum(TwoSum.java:3)