G641. Missing Ranges

Code(Language:C++) (Judger:ip-172-31-12-4)

class Solution {
public:
    /*
     * @param nums: a sorted integer array
     * @param lower: An integer
     * @param upper: An integer
     * @return: a list of its missing ranges
     */
    vector<string> findMissingRanges(vector<int> &nums, int lower, int upper) {
        // write your code here
        vector<string> res; 
        if(upper < lower){
            return res; 
        }
        const int size = nums.size();
        if(size == 0){
            if(upper != lower){
               res.push_back(to_string(lower) + "->" + to_string(upper)); 
            }
            else{
                res.push_back(to_string(lower)); 
            }
            return res; 
        }
        if(lower > nums[size - 1] || upper < nums[0]){
            return res; 
        }
        if(lower != nums[0]){
            long long pre = nums[0]; 
            if(pre - 1 == lower){
               res.push_back(to_string(lower)); 
            }
            else{
                res.push_back(to_string(lower) + "->" + to_string(pre - 1)); 
            }
        }
        for(int i = 1; i < size; i++){
            long long pre = nums[i - 1];
            long long cur = nums[i]; 
            if(cur - pre <= 1){
                continue; 
            }
            if(cur - pre == 2){
                res.push_back(to_string(cur - 1)); 
            }
            else{
                res.push_back(to_string(pre + 1) + "->" + to_string(cur - 1)); 
            }
        }
        if(upper != nums[size - 1]){
            long long cur = nums[size - 1]; 
            if(cur + 1 == upper){
                res.push_back(to_string(upper)); 
            }
            else{
                res.push_back(to_string(cur + 1) + "->" +to_string(upper)); 
            }
        }
        return res; 
    }
};

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61