Leetcode 228. Summary Ranges

228. Summary Ranges

• Total Accepted: 51769
• Total Submissions: 203058
• 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：见代码。

注意c++中数字转换为string可以用to_string()函数。

实现string和int的相互转换可以用stringstream。

代码：

用to_string()函数：

class Solution {
public:
    vector<string> summaryRanges(vector<int>& nums) {
        int low=0,high=0,n=nums.size(),i;
        vector<string> res;
        string lows,highs;
        while(high<n){
            lows=to_string(nums[low]);
            i=0;
            while(high<n&&nums[low]+i==nums[high]){
                i++;
                high++;
            }
            if(i>1){
                highs=to_string(nums[high-1]);
                lows=lows+"->"+highs;
            }
            res.push_back(lows);
            low=high;
        }
        return res;
    }
};

用stringstream：如果想通过使用同一stringstream对象实现多种类型的转换，请注意在每一次转换之后都必须调用clear()成员函数

class Solution {
public:
    vector<string> summaryRanges(vector<int>& nums) {
        int low=0,high=0,n=nums.size(),i;
        vector<string> res;
        stringstream ss;
        string lows,highs;
        while(high<n){
            ss<<nums[low];
            ss>>lows;
            ss.clear();
            i=0;
            while(high<n&&nums[low]+i==nums[high]){
                i++;
                high++;
            }
            if(i>1){
                ss<<nums[high-1];
                ss>>highs;
                ss.clear();
                lows=lows+"->"+highs;
            }
            res.push_back(lows);
            low=high;
        }
        return res;
    }
};