加起来和为目标值的组合

package main

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param target int整型 
 * @param nums int整型一维数组 
 * @return int整型二维数组
*/
func combinationCount( target int ,  nums []int ) [][]int {
    ans:=[][]int{}
    var dfs func([]int,int,int)
    dfs=func(path []int,sum int,idx int){
        if sum>=target{
            if sum==target{
                tmp:=make([]int,len(path))
                copy(tmp,path)
                ans=append(ans,tmp)
            }
            return
        }
        for i:=idx;i<len(nums);i++{
            path=append(path,nums[i])
            sum+=nums[i]
            dfs(path,sum,i)
            path=path[:len(path)-1]
            sum-=nums[i]
        }
    }
    dfs([]int{},0,0)
    return ans
}