题解 | #和为S的连续正数序列#

import java.util.ArrayList;
public class Solution {
    ArrayList<ArrayList<Integer>> res = new ArrayList<>();
    public ArrayList<ArrayList<Integer>> FindContinuousSequence(int n) {
        if (n <= 1) return res;
        //用滑动窗口
        int l = 0;
        int r = 0;
        int sum = 0;
        while (r < n){
            while (sum >= n){
                l++;
                sum -= l;
                if (sum == n){
                    add(l, r);
                }
            }
            while (sum < n){
                r++;
                sum += r;
                if (sum == n){
                    add(l, r);
                }
            }
        }
        return res;
    }

    private void add(int l, int r){
        ArrayList<Integer> tmp = new ArrayList<>();
        for (int i = l + 1; i <= r; i++){
            tmp.add(i);
        }
        res.add(tmp);
    }
}