规范格式

leetcode/0996.Number-of-Squareful-Arrays/996. Number of Squareful Arrays.go

@@ -0,0 +1,58 @@
+package leetcode
+
+import (
+	"math"
+	"sort"
+)
+
+func numSquarefulPerms(A []int) int {
+	if len(A) == 0 {
+		return 0
+	}
+	used, p, res := make([]bool, len(A)), []int{}, [][]int{}
+	sort.Ints(A) // 这里是去重的关键逻辑
+	generatePermutation996(A, 0, p, &res, &used)
+	return len(res)
+}
+
+func generatePermutation996(nums []int, index int, p []int, res *[][]int, used *[]bool) {
+	if index == len(nums) {
+		checkSquareful := true
+		for i := 0; i < len(p)-1; i++ {
+			if !checkSquare(p[i] + p[i+1]) {
+				checkSquareful = false
+				break
+			}
+		}
+		if checkSquareful {
+			temp := make([]int, len(p))
+			copy(temp, p)
+			*res = append(*res, temp)
+		}
+		return
+	}
+	for i := 0; i < len(nums); i++ {
+		if !(*used)[i] {
+			if i > 0 && nums[i] == nums[i-1] && !(*used)[i-1] { // 这里是去重的关键逻辑
+				continue
+			}
+			if len(p) > 0 && !checkSquare(nums[i]+p[len(p)-1]) { // 关键的剪枝条件
+				continue
+			}
+			(*used)[i] = true
+			p = append(p, nums[i])
+			generatePermutation996(nums, index+1, p, res, used)
+			p = p[:len(p)-1]
+			(*used)[i] = false
+		}
+	}
+	return
+}
+
+func checkSquare(num int) bool {
+	tmp := math.Sqrt(float64(num))
+	if int(tmp)*int(tmp) == num {
+		return true
+	}
+	return false
+}