# 2.1.backtracking

- [2.1.1.連續序列的排列組合(可能會重複)](/letcode/2.algorithm/2.1.backtracking/211lian-xu-xu-lie-de-pai-lie-zu-540828-ke-neng-hui-zhong-890729.md)
- [2.1.3.一串數列中任取n個數字, 總共有幾種組合](/letcode/2.algorithm/2.1.backtracking/213yi-chuan-shu-lie-zhong-ren-qu-n-ge-shu-5b572c-zong-gong-you-ji-zhong-zu-he.md)
- [2.1.2.一串數列中取n個數字, 共有幾種組合](/letcode/2.algorithm/2.1.backtracking/212yi-chuanshu-lie-zhong-qu-n-ge-shu-5b572c-gong-you-ji-zhong-zu-he.md)