剑指 Offer 57

List<List<Integer>> res = new ArrayList<>();
    public int[][] findContinuousSequence(int target) {

        List<Integer> list = new ArrayList<>();
        findOne(target);
        int l = res.size();
        if(l == 0) return new int[0][0];
        int[][] res = new int[l][];
        for(int i = 0;i<l;i++){
            List<Integer> y = this.res.get(i);
            int len = y.size();
            int[] r = new int[len];
            for(int j = 0;j<len;j++){
                r[j] = y.get(j);
            }
            res[i] = r;
        }
        return res;
    }

    private void findOne(int target) {
        int j = 1;
        while(j<=target/2) {
            int i = j;
            int m = target;
            List<Integer> list = new ArrayList<>();
            while (i <= target / 2 + 1) {
                if (i < m) {
                    list.add(i);
                    m = m - i;
                    i++;
                } else if (i == m) {
                    list.add(i);
                    res.add(list);
                    j++;
                    break;
                }else{
                    j++;
                    break;
                }
            }
        }
    }

List<int[]> res = new ArrayList<>();
public int[][] findContinuousSequence(int target) {  //方法2-------------------------------------------------------------
    //双指针
    if(target<3) return new int[0][0];
    int small = 1;
    int big = 2;
    int mid = (1+target)/2;
    int curSum = small + big;
    while (small<target) {
        if(curSum == target){
            //将从small到big的连续数字组成的数组添加进去；
            addList(small,big);
        }
        while (curSum>target && small<mid){
            curSum -= small;
            small ++;

            if(curSum == target){
                //将从small到big的连续数字组成的数组添加进去；
                addList(small,big);
            }
        }
        big ++;
        curSum += big;
    }
    int[][] x = new int[res.size()][];
    for(int i = 0;i<res.size();i++){
        x[i] = res.get(i);
    }
    return x;
}

private void addList(int small,int big){
    int[] nums = new int[big-small+1];
    int i = 0;
    while(i<big-small+1){
        nums[i] = small;
        small++;
        i++;
    }
    res.add(nums);
}

 

 双指针