Summary Ranges 解答

Question

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"].

Solution

Traverse array, remember not to forget the last element.

 public class Solution {
     public List<String> summaryRanges(int[] nums) {
         int length = nums.length;
         List<String> result = new ArrayList<String>();
         if (length == 0)
             return result;
         StringBuffer tmp = new StringBuffer();
         int startNum = nums[0];
         int endNum = nums[0];
         if (length == 1) {
             tmp.append(startNum);
             result.add(tmp.toString());
             return result;
         }
         for (int i = 0; i < length - 1; i++) {
             if (nums[i] != nums[i + 1] - 1) {
                 tmp = new StringBuffer();
                 endNum = nums[i];
                 if (startNum == endNum) {
                     tmp.append(startNum);
                 } else {
                     tmp.append(startNum);
                     tmp.append("->");
                     tmp.append(endNum);
                 }
                 result.add(tmp.toString());
                 startNum = nums[i + 1];
             }
         }
         tmp = new StringBuffer();
         endNum = nums[length - 1];
         if (startNum == endNum) {
             tmp.append(startNum);
         } else {
             tmp.append(startNum);
             tmp.append("->");
             tmp.append(endNum);
         }
         result.add(tmp.toString());
         return result;
     }
 }