规范格式

leetcode/0526.Beautiful-Arrangement/526. Beautiful Arrangement.go

@@ -0,0 +1,50 @@
+package leetcode
+
+// 解法一 暴力打表法
+func countArrangement1(N int) int {
+	res := []int{0, 1, 2, 3, 8, 10, 36, 41, 132, 250, 700, 750, 4010, 4237, 10680, 24679, 87328, 90478, 435812}
+	return res[N]
+}
+
+// 解法二 DFS 回溯
+func countArrangement(N int) int {
+	if N == 0 {
+		return 0
+	}
+	nums, used, p, res := make([]int, N), make([]bool, N), []int{}, [][]int{}
+	for i := range nums {
+		nums[i] = i + 1
+	}
+	generatePermutation526(nums, 0, p, &res, &used)
+	return len(res)
+}
+
+func generatePermutation526(nums []int, index int, p []int, res *[][]int, used *[]bool) {
+	if index == len(nums) {
+		temp := make([]int, len(p))
+		copy(temp, p)
+		*res = append(*res, temp)
+		return
+	}
+	for i := 0; i < len(nums); i++ {
+		if !(*used)[i] {
+			if !(checkDivisible(nums[i], len(p)+1) || checkDivisible(len(p)+1, nums[i])) { // 关键的剪枝条件
+				continue
+			}
+			(*used)[i] = true
+			p = append(p, nums[i])
+			generatePermutation526(nums, index+1, p, res, used)
+			p = p[:len(p)-1]
+			(*used)[i] = false
+		}
+	}
+	return
+}
+
+func checkDivisible(num, d int) bool {
+	tmp := num / d
+	if int(tmp)*int(d) == num {
+		return true
+	}
+	return false
+}