A sequence of consecutive positive numbers whose sum is S

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It's been a long time since I wrote double pointers, so I forgot. In fact, this doesn't count. I just specify a window and save all the numbers from left to right in the middle. I thought it was done in two. . .

class Solution {
public:
    vector<vector<int> > FindContinuousSequence(int sum) {
        vector<vector<int> > ans;
        int l = 1, r = 2;
        int val = 0;
        while(l < r) {
            int num = (l + r) *(r - l + 1) / 2;
            if(num == sum) {
                vector<int> tep;
                for(int i = l; i <= r; i++) {
                    tep.push_back(i);
                }
                ans.push_back(tep);
                l++;
            }
            else if(num > sum) {
                l++;
            }
            else {
                r++;
            }
        }
        return ans;
    }
};