输入：15

输出：[[1,2,3,4,5],[4,5,6],[7,8]]

import java.util.ArrayList;

public class Solution {

    public ArrayList<ArrayList<Integer> > FindContinuousSequence(int sum) {

       ArrayList<ArrayList<Integer>> res = new ArrayList<>();

        if(sum<3){

            return res;

        }

        int p=1, q=2;

        int mid = (1+sum) >> 1;  //

        int curSum = p + q;

        while(p < mid){

            while(curSum > sum && p < mid){

                curSum -= p;

                p++;

                //if(curSum == sum){

               //     res.add(getList(p, q));

               // }

            }

            //这段代码不要上一个while之前，不然会代码重复，而且多了一次判断，效率不高

            if(curSum == sum){

                res.add(getList(p, q));

            }

            ++q;

            curSum += q;

        }

        return res;

    }

    private ArrayList<Integer> getList(int l, int r){

        ArrayList<Integer> res = new ArrayList<>();

        for(int i=l; i<=r; i++){

            res.add(i);

        }

        return res;

    }

}