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;
    }
}