228. Summary Ranges

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”].

// Integer.toString(nums[s])
// Java 中简便的转换方法

public class Solution {
    public List summaryRanges(int[] nums) {
        List res = new ArrayList<>();
        if (nums == null || nums.length < 1){
            return res;
        }
        int s = 0, e = 0;
        while(e < nums.length){
            if(e + 1 < nums.length && nums[e + 1] == nums[e] + 1){
                 e++;
             } else {
                 if(s == e){
                     res.add(Integer.toString(nums[s]));
                 } else {
                     String str = nums[s] + "->" + nums[e];
                     res.add(str);
                }
                e++;
                s = e;
            }
        }
        return res;
    }
}