LeetCode 228: Summary Ranges

228. Summary Ranges

Difficulty: Medium
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”].

思路

由于数组元素已排好序，而且没有重复元素，思路便蛮简单，顺序遍历数组，只要正在遍历的元素不比上一个元素大1，则上一元素是上一范围的右端点，正在遍历的元素是下一范围的左端点。

代码

[c++]

class Solution {public:    vector<string> summaryRanges(vector<int>& nums) {        vector<string> res;        if (nums.size() <= 0)            return res;        int index = 0;        for (int i = 0; i < nums.size(); ++i) {            if (i > 0 && nums[i] > nums[i - 1] + 1) {                string str = to_string(nums[index]);                if (index != i - 1) {                    str += "->";                    str += to_string(nums[i - 1]);                }                res.push_back(str);                index = i;            }        }        string str = to_string(nums[index]);        if (index != nums.size() - 1) {            str += "->";            str += to_string(nums[nums.size() - 1]);        }        res.push_back(str);        return res;    }};