【LeetCode】228 - Summary Ranges

最新推荐文章于 2023-04-23 15:02:13 发布

weixin_33912246

最新推荐文章于 2023-04-23 15:02:13 发布

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原文链接：http://www.cnblogs.com/irun/p/4687845.html

本文提供了一种高效的方法来解决给定已排序且不含重复元素的整数数组的区间求和问题。通过示例说明如何返回数组的有效区间表示，如 [0,1,2,4,5,7] 对应的区间表示为 [0->24->57]。文章给出了两种解决方案，包括一种简洁的 C++ 实现。

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"].

My Solution:

vector<string> summaryRanges(vector<int>& nums)
    {
        vector<string> ret;
        if(nums.empty())return ret;
        int low=nums[0];
        bool flag=false;
        for(int i=1;i<nums.size();i++){
            while(i<nums.size() && nums[i]==nums[i-1]+1)i++;
            int high=nums[i-1];
            if(low!=high)
　　　　　　　　　ret.push_back(to_string(low)+"->"+to_string(high));
            else
                ret.push_back(to_string(low));
            if(i==nums.size()){
                flag=true;
                break;
            }
            low=nums[i];
        }
        if(flag==false)ret.push_back(to_string(low));
        return ret;
    }

Better Solution:

 1 class Solution {
 2 public:
 3     vector<string> summaryRanges(vector<int>& nums) {    
 4         vector<string> vec;
 5         if(nums.empty())
 6             return vec;
 7     
 8         int low=nums[0],high=nums[0];
 9         for(int i = 1; i < nums.size(); i ++)
10         {
11             if(nums[i]-nums[i-1] == 1)high=nums[i];
12             else
13             {
14                 string range;
15                 if(low != high)
16                     range = to_string(low) + "->" + to_string(high);
17                 else
18                     range = to_string(low);
19                 vec.push_back(range);
20                 low = nums[i];
21                 high = nums[i];
22             }
23         }
24         string range;
25         if(low != high)
26             range = to_string(low) + "->" + to_string(high);
27         else
28             range = to_string(low);
29         vec.push_back(range);
30         return vec;
31     }
32 };