Input: nums = [0,1,2,4,5,7] Output: ["0->2","4->5","7"] public class DemoApplication { public static void main(String[] args) { int[] nums = {0,1,2,4,6,5,7,10}; System.out.println(summary(nums)); } public static List<String> summary(int[] nums){ List<String> result = new ArrayList<>(); int i = 0; int n = nums.length; while (i < n) { int start = nums[i]; while (i + 1 < n && nums[i+1] == nums[i] + 1){ i++; } int end = nums[i]; if (start == end){ result.add(String.valueOf(start)); } else { result.add(start + "->" + end); } i++; } return result; } }