Description
tag: array , backtraking
difficulty : medium
代码语言：javascript复制Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.
Each number in candidates may only be used once in the combination.
Note:
All numbers (including target) will be positive integers.
The solution set must not contain duplicate combinations.
Example 1:
Input: candidates = [10,1,2,7,6,1,5], target = 8,
A solution set is:
[
[1, 7],
[1, 2, 5],
[2, 6],
[1, 1, 6]
]
Example 2:
Input: candidates = [2,5,2,1,2], target = 5,
A solution set is:
[
[1,2,2],
[5]
]Solution
代码语言：javascript复制var results [][]int
var existed map[string]int
func combinationSum2(candidates []int, target int) [][]int {
results = make([][]int, 0)
if len(candidates) == 0 {
return results
}
existed = make(map[string]int)
sort.Ints(candidates)
backtrack(candidates, target, nil)
return results
}
func backtrack(candidates []int, target int, result []int){
for i, val := range candidates {
if val == target {
result = append(result, val)
temp := make([]int, len(result))
copy(temp, result)
addIfNotExist(temp)
break
}
if val < target {
result = append(result, val)
backtrack(candidates[i 1:], target - val, result)
result = result[:len(result)-1]
}
if val > target {
break
}
}
}
func addIfNotExist(cr []int){
sort.Ints(cr)
var s string = ""
for _, val := range cr {
s = "," string(val)
}
if _,ok := existed[s];ok {
return
}
results = append(results, cr)
existed[s] = 1
}Note:
- almost same with 39
- element can be used only once
