【LeetCode】Missing Ranges

Missing Ranges

Given a sorted integer array where the range of elements are [lower, upper] inclusive, return its missing ranges.

For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74", "76->99"].

 

逐个数组元素遍历，将间隙取出即可。注意两边的情况。

class Solution {

public:

    vector<string> findMissingRanges(int A[], int n, int lower, int upper)

    {

        vector<string> ret;

        if(n == 0)

            return ret;

        string str;

        if(lower < A[0])

        {

            if(lower < A[0]-1)

                str = to_string((long long)lower) + "->" + to_string((long long)A[0]-1);

            else

                //lower == A[0]-1

                str = to_string((long long)lower);

            ret.push_back(str);

        }

        for(int i = 1; i < n; i ++)

        {

            if(A[i] - A[i-1] < 2)

                continue;



            if(A[i] - A[i-1] > 2)

                str = to_string((long long)A[i-1]+1) + "->" + to_string((long long)A[i]-1);

            else

                //A[i] - A[i-1] == 2

                str = to_string((long long)A[i-1]+1);

            ret.push_back(str);

        }

        if(A[n-1] < upper)

        {

            if(A[n-1] < upper-1)

                str = to_string((long long)A[n-1]+1) + "->" + to_string((long long)upper);

            else

                //upper == A[n-1]+1

                str = to_string((long long)upper);

            ret.push_back(str);

        }

        return ret;

    }

};

 

以下是我的测试用例，全部通过：

void display(vector<string>& ret)

{

    for(int i = 0; i < ret.size(); i ++)

    {

        cout << ret[i] << " ";

    }

    cout << endl;

}



int main()

{

    Solution s;

    int A[1];

    //expect: ["0->9"]

    vector<string> ret = s.findMissingRanges(A, 0, 0, 9);

    display(ret);



    int B[1] = {6};

    //expect: ["0->5", "7->9"]

    ret = s.findMissingRanges(B, 1, 0, 9);

    display(ret);



    int C[3] = {0, 1, 2};

    //expect: []

    ret = s.findMissingRanges(C, 3, 0, 2);

    display(ret);



    int D[5] = {0, 1, 3, 50, 75};

    //expect: ["2", "4->49", "51->74", "76->99"]

    ret = s.findMissingRanges(D, 5, 0, 99);

    display(ret);

}