mirror of
https://github.com/halfrost/LeetCode-Go.git
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27 lines
539 B
Go
27 lines
539 B
Go
package leetcode
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func combine(n int, k int) [][]int {
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if n <= 0 || k <= 0 || k > n {
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return [][]int{}
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}
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c, res := []int{}, [][]int{}
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generateCombinations(n, k, 1, c, &res)
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return res
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}
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func generateCombinations(n, k, start int, c []int, res *[][]int) {
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if len(c) == k {
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b := make([]int, len(c))
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copy(b, c)
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*res = append(*res, b)
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return
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}
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// i will at most be n - (k - c.size()) + 1
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for i := start; i <= n-(k-len(c))+1; i++ {
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c = append(c, i)
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generateCombinations(n, k, i+1, c, res)
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c = c[:len(c)-1]
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}
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return
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}
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