1class SummaryRanges {
2    constructor() {
3        this.intervals = [];
4    }
5
6    addNum(value) {
7        for (let interval of this.intervals) {
8            if (interval[0] <= value && value <= interval[1]) {
9                return;
10            }
11            if (interval[0] === value + 1) {
12                interval[0] = value;
13                this.merge();
14                return;
15            }
16            if (interval[1] === value - 1) {
17                interval[1] = value;
18                this.merge();
19                return;
20            }
21        }
22        this.intervals.push([value, value]);
23        this.intervals.sort((a, b) => a[0] - b[0]);
24    }
25
26    getIntervals() {
27        return this.intervals;
28    }
29
30    merge() {
31        let merged = [];
32        for (let interval of this.intervals) {
33            if (merged.length === 0 || merged[merged.length - 1][1] < interval[0] - 1) {
34                merged.push(interval);
35            } else {
36                merged[merged.length - 1][1] = Math.max(merged[merged.length - 1][1], interval[1]);
37            }
38        }
39        this.intervals = merged;
40    }
41}

1#include <map>
2#include <vector>
3
4using namespace std;
5
6class SummaryRanges {
private:
    map<int, int> intervals;

public:
    SummaryRanges() {}

    void addNum(int val) {
        if (intervals.count(val)) return;

        auto l = intervals.lower_bound(val);
        auto h = intervals.upper_bound(val);

        if (l != intervals.begin() && prev(l)->second >= val - 1) {
            --l;
        }

        if (l != intervals.end() && l->second < val - 1) {
            l = intervals.end();
        }

        int start = val, end = val;

        if (l != intervals.end() && l->first <= val && l->second >= val) {
            return;
        }

        if (l != intervals.end() && l->first <= val + 1) {
            start = l->first;
            intervals.erase(l);
        }

        if (h != intervals.end() && h->first <= val + 1) {
            end = h->second;
            intervals.erase(h);
        }

        intervals[start] = end;
    }

    vector<vector<int>> getIntervals() {
        vector<vector<int>> res;
        for (const auto& [key, val] : intervals) {
            res.push_back({key, val});
        }
        return res;
    }
};