【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 == )
            return ret;
        string str;
        if(lower < A[])
        {
            if(lower < A[]-)
                str = to_string((long long)lower) + "->" + to_string((long long)A[]-);
            else
                //lower == A[0]-1
                str = to_string((long long)lower);
            ret.push_back(str);
        }
        for(int i = ; i < n; i ++)
        {
            if(A[i] - A[i-] < )
                continue;

            if(A[i] - A[i-] > )
                str = to_string((long long)A[i-]+) + "->" + to_string((long long)A[i]-);
            else
                //A[i] - A[i-1] == 2
                str = to_string((long long)A[i-]+);
            ret.push_back(str);
        }
        if(A[n-] < upper)
        {
            if(A[n-] < upper-)
                str = to_string((long long)A[n-]+) + "->" + 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 = ; i < ret.size(); i ++)
    {
        cout << ret[i] << " ";
    }
    cout << endl;
}

int main()
{
    Solution s;
    int A[];
    //expect: ["0->9"]
    vector<string> ret = s.findMissingRanges(A, , , );
    display(ret);

    int B[] = {};
    //expect: ["0->5", "7->9"]
    ret = s.findMissingRanges(B, , , );
    display(ret);

    int C[] = {, , };
    //expect: []
    ret = s.findMissingRanges(C, , , );
    display(ret);

    int D[] = {, , , , };
    //expect: ["2", "4->49", "51->74", "76->99"]
    ret = s.findMissingRanges(D, , , );
    display(ret);
}