Summary Ranges

Problem Statement

Given a sorted integer array without duplicates, return the summary of its ranges.

For example, given [0,1,2,4,5,7], return ["0->2","4->5","7"].

Run Time Complexity

O(n)

Code

public class Solution {
    public List<String> summaryRanges(int[] nums) {
        if(nums.length < 1){
            return new ArrayList<String>();
        }
        List<String> result = new ArrayList<String>();
        int start = nums[0];
        int previous = nums[0];
        for(int i = 1; i< nums.length; i++){
            if(nums[i] - previous > 1 || nums[i] - previous < 1){
                if(start != previous){
                    result.add(start+"->"+previous);
                }else{
                    result.add(""+start);
                }
                start = nums[i];
                previous = nums[i];
            }
            if(nums[i] - previous == 1){
                previous = nums[i];
            }
        }
        
        if(previous != start){
            result.add(new String(start+"->"+previous));
        }else{
            result.add(new String(""+start));
        }
        return result;
    }
}