Given a very large array of integers (sorted, no duplicates), ouput all the possible combinations (a, b, c) such that a + b = c. No other data storage should be used.
Example:
[1, 2, 3, 4, 5, 7, 8, 9, 11, ....]
Output: [[1, 2, 3], [1, 3, 4], [1, 7, 8], [1, 8, 9], [2, 3, 5],...]
My solution:
public List<List<Integer>> solution(int[] nums) {
List<List<Integer>> result = new ArrayList<>();
for (int i = 0; i < nums.length - 2; i++) {
int j = i + 1;
int k = j + 1;
while (j < k) {
int target = nums[i] + nums[j];
while (k < nums.length && nums[k] <= target) {
if (nums[k] == target) {
result.add(Arrays.asList(new Integer[]{nums[i], nums[j], nums[k]}));
break;
}
k++;
}
j++;
}
}
return result;
}I was thinking of the best solution I could find for 3Sum which is O(n^2) (CMIIW) but interviewer wants better solution.
How to make this more efficient?
[EDIT] My solution is O(n^3) which I mistakenly thought was O(n^2)
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