LeetCode: 228. Summary Ranges

题目描述

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

Example 1:

Input:  [0,1,2,4,5,7]
Output: ["0->2","4->5","7"]
Explanation: 0,1,2 form a continuous range; 4,5 form a continuous range.

Example 2:

Input:  [0,2,3,4,6,8,9]
Output: ["0","2->4","6","8->9"]
Explanation: 2,3,4 form a continuous range; 8,9 form a continuous range.

解题思路

统计连续的数字，根据题意将相邻的连续数字拼接。

AC 代码

class Solution {
public:
    vector<string> summaryRanges(vector<int>& nums) {
        vector<string> ranges;
        int startIdx = 0;
        int cnt = 0;
        
        if(nums.empty()) return ranges;
        while(startIdx+cnt <= nums.size())
        {
            if(startIdx+cnt == nums.size() || nums[startIdx]+cnt != nums[startIdx+cnt])
            {
                if(startIdx+cnt == nums.size() && cnt == 0)
                {
                    break;
                }
                
                ranges.push_back(to_string(nums[startIdx]));
                if(cnt > 1)
                {
                    ranges.back() += ("->"+to_string(nums[startIdx+cnt-1]));
                }
                
                startIdx = startIdx+cnt;
                cnt = 0;
            }
            else
            {
                ++cnt;
            }
        }
        
        return ranges;
    }
};