【劍指offer】：和爲s的連續正數序列

297. 和爲s的連續正數序列

問題描述：

輸入一個正整數 target ，輸出所有和爲 target 的連續正整數序列（至少含有兩個數）。

序列內的數字由小到大排列，不同序列按照首個數字從小到大排列。

示例1

輸入：target = 9
輸出：[[2,3,4],[4,5]]

示例1

輸入：target = 15
輸出：[[1,2,3,4,5],[4,5,6],[7,8]]

完整代碼：

    // Encodes a tree to a single string.
class Solution {
    public int[][] findContinuousSequence(int target) {
        if (target < 3)
            return null;
        int small = 1 , big = 2;
        int curr = small + big;
        List<int[]> res = new ArrayList<>();
        int middle = (target+1)>>>1;
        while (small < middle) {
            if (curr == target){
                int tmp[] = new int[big - small + 1];
                for (int i = small,j = 0;i <= big; i++,j++) {
                    tmp[j] = i;
                }
                res.add(tmp);
            }
            while (curr > target && small < middle) {
                curr -= small;
                small++;
                if (curr == target){
                    int tmp[] = new int[big - small + 1];
                    for (int i = small,j = 0;i <= big; i++,j++) {
                        tmp[j] = i;
                    }
                    res.add(tmp);
                }
            }
            big++;
            curr+=big;
        }

        return res.toArray(new int[0][]);
    }
}

附加GitHub鏈接