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🐱(backtrace): 216. 组合总和 III

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`@@ -83,4 +83,56 @@ class Solution:`
`83`	`83`	`track = []`
`84`	`84`	`track_back(nums, track)`
`85`	`85`	`return ans`
	`86`	+```
	`87`	`+`
	`88`	`+## 216. 组合总和 III`
	`89`	`+`
	`90`	`+[原题链接](https://leetcode-cn.com/problems/combination-sum-iii/)`
	`91`	`+`
	`92`	`+回溯模板:`
	`93`	`+`
	`94`	+```
	`95`	`+backtracking() {`
	`96`	`+ if (终止条件) {`
	`97`	`+ 存放结果;`
	`98`	`+ }`
	`99`	`+`
	`100`	`+ for (选择:选择列表(可以想成树中节点孩子的数量)) {`
	`101`	`+ 递归,处理节点;`
	`102`	`+ backtracking();`
	`103`	`+ 回溯,撤销处理结果`
	`104`	`+ }`
	`105`	`+}`
	`106`	+```
	`107`	`+`
	`108`	`+### 题解`
	`109`	`+`
	`110`	+```python
	`111`	`+class Solution:`
	`112`	`+ def combinationSum3(self, k: int, n: int) -> List[List[int]]:`
	`113`	`+ ans = []`
	`114`	`+ '''`
	`115`	`+ element: 数组内答案`
	`116`	`+ start: 遍历的开始位置`
	`117`	`+ num: 剩余数字`
	`118`	`+ '''`
	`119`	`+ def dfs(element, start, num):`
	`120`	`+ # 符合条件,加入最终答案,结束递归`
	`121`	`+ if len(element) == k or num < 0:`
	`122`	`+ if len(element) == k and num == 0:`
	`123`	`+ # print(element)`
	`124`	`+ # 深拷贝`
	`125`	`+ ans.append(element[:])`
	`126`	`+ return`
	`127`	`+`
	`128`	`+ for i in range(start, 10):`
	`129`	`+ # 加入当前值`
	`130`	`+ element.append(i)`
	`131`	`+ # 递归`
	`132`	`+ dfs(element, i + 1, num - i)`
	`133`	`+ # 撤销选择,即回溯`
	`134`	`+ element.pop()`
	`135`	`+`
	`136`	`+ dfs([], 1, n)`
	`137`	`+ return ans`
`86`	`138`	```

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