part 1 complete but i didn't make permutations myself

day7/part1/permutations/permutations.go

@@ -1,26 +1,59 @@
 package permutations
 
 // CreatePermutations will return a 2D slice containing permutations from zero to the inputted int
-func CreatePermutations(size int) []string {
-	result := make([]string, 0)
+// func CreatePermutations(size int) [][]int {
+// 	result := make([][]int, 0)
 
-	pointerToResult := &result
-	onePerm(pointerToResult, "01234")
+// helper := func(digits []int, builder []int) {
 
+// 	newDigits := make([]int, len(digits))
+// 	copy(newDigits, digits)
+
+// 	if len(digits) == 0 {
+// 		// use the reference point in memory
+// 		result = append(result, builder)
+// 	} else {
+// 		for index, digit := range newDigits {
+// 			fmt.Println("append", append(newDigits[:index], newDigits[index+1:]...))
+// 			fmt.Println("builder", append(builder, digit))
+// 			helper(append(newDigits[:index], newDigits[index+1:]...), append(builder, digit))
+// 			// fmt.Println("looping")
+// 		}
+// 	}
+
+// }
+
+// helper([]int{0, 1, 2, 3, 4}, make([]int, 0))
+
+// 	return result
+// }
+
+func nextPerm(p []int) {
+	for i := len(p) - 1; i >= 0; i-- {
+		if i == 0 || p[i] < len(p)-i-1 {
+			p[i]++
+			return
+		}
+		p[i] = 0
+	}
+}
+
+func getPerm(orig, p []int) []int {
+	result := append([]int{}, orig...)
+	for i, v := range p {
+		result[i], result[i+v] = result[i+v], result[i]
+	}
 	return result
 }
 
-func onePerm(resultSlice *[]string, substring string) {
-	// if len(*resultSlice) == 0 {
-	// 	for i := 0; i < len(substring); i++ {
-	// 		*resultSlice = append(*resultSlice, string(substring[i]))
-	// 	}
-	// 	return
-	// }
-	// for i := 0; i < len(*resultSlice); i++ {
-	// 	newSubstring := *resultSlice[i]
-	// }
-	// modify the actual data @ the location in memory
-	// fmt.Println(resultSlice, *resultSlice)
+// CreatePermutations docz
+func CreatePermutations() [][]int {
+	orig := []int{0, 1, 2, 3, 4}
+	results := make([][]int, 0)
 
+	for p := make([]int, len(orig)); p[0] < len(p); nextPerm(p) {
+		// fmt.Println(getPerm(orig, p))
+		results = append(results, getPerm(orig, p))
+	}
+	return results
 }