LeetCode讲解篇之77. 组合

题目描述

题解思路

遍历nums，让当前数字添加到结果前缀中，递归调用，直到前缀的长度为k，然后将前缀添加到结果集

题解代码

func combine(n int, k int) [][]int {
    var nums = make([]int, n)
    for i := n; i > 0; i-- {
        nums[i-1] = i
    }
    var res = make([][]int, 0)
    var dfs func(prefix []int, nums []int, k int)
    dfs = func(prefix []int, nums []int, k int) {
        if k == 0 {
            tmp := make([]int, len(prefix))
            copy(tmp[:], prefix[:])
            res = append(res, tmp)
            return
        }
        for i := 0; i <= len(nums) - k; i++ {
            dfs(append(prefix, nums[i]), nums[i+1:], k-1)
        }
    }
    dfs(make([]int, 0, k), nums, k)
    return res
}