39. Combination Sum
Given a set of candidate numbers (candidates) (without duplicates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.
The same repeated number may be chosen from candidates unlimited number of times.
Note:
- All numbers (including
target) will be positive integers. - The solution set must not contain duplicate combinations.
Example 1:
代码语言：javascript复制Input: candidates = [2,3,6,7], target = 7,
A solution set is:
[
[7],
[2,2,3]
]Example 2:
代码语言：javascript复制Input: candidates = [2,3,5], target = 8,
A solution set is:
[
[2,2,2,2],
[2,3,3],
[3,5]
]思路：
题目意思是找出数组中所有能组合成target的组合，典型的回溯题目，递归枚举所有结果即可。
代码：
代码语言：javascript复制func combinationSum(candidates []int, target int) [][]int {
var res [][]int
if candidates == nil || len(candidates) == 0 {
return res
}
dfs(&res, []int{}, candidates, target, 0)
return res
}
func dfs(res *[][]int, temp []int, nums []int, target int, start int) {
if target < 0 {
return
}
if target == 0 {
*res = append(*res, append([]int{}, temp...))
}
for i := start; i < len(nums); i {
temp = append(temp, nums[i]);
dfs(res, temp, nums, target - nums[i], i)
temp = temp[:len(temp)-1]
}
}
