剑指 Offer 57 - II. 和为s的连续正数序列

class Solution {
public:
    vector<vector<int>> findContinuousSequence(int sum) {
        vector<vector<int>> ans;
        vector<int> res;
        int l = 1, r = 1, s = 1;
        while (r < sum) {
            while (s < sum) r++, s += r;
            if (s == sum) {
                res.clear();
                for (int i = l; i <= r; i++)
                    res.push_back(i);
                ans.push_back(res);
            }
            
            s -= l;
            l++;
        }
    
        return ans;
    }
};