题解 | #牛棚分组#

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 n int整型 
 * @param k int整型 
 * @return int整型二维数组
*/
func combine( n int ,  k int ) [][]int {
    // write code here
    res :=make([][]int ,0 )   
    solution :=make([]int, 0)
    backtrack(&res, solution, 1, n, k)
    return res
}

func backtrack(res *[][]int ,solution []int,start,n,k int){
    if k==0{
        temp :=make([]int, len(solution))
        copy(temp, solution)
        *res=append(*res, temp)
        return
    }
    for i :=start;i<=n;i++{
        solution = append(solution, i)
        backtrack(res, solution ,i+1, n, k-1)
        solution = solution[:len(solution)-1]
    }
}