Add verify-preorder-serialization-of-a-binary-tree

Author: beyondyyh

algorithms/binarysearch/69.mySqrt.go

@@ -1,7 +1,5 @@
 package binarysearch
 
-import _ "fmt"
-
 func mySqrt(x int) int {
 	left, right := 0, x
 	for left < right {

algorithms/linkedList/19.removeNthFromEnd_test.go

@@ -19,6 +19,7 @@ type (
 	}
 )
 
+// go test -v base.go 19.*
 func build_removeNthFromEnd_case() []entry19 {
 	cases := []entry19{
 		{

algorithms/tree/331.isValidSerialization.go

@@ -0,0 +1,26 @@
+package tree
+
+import "strings"
+
+func isValidSerialization(preorder string) bool {
+	var leaves, node int
+	pres := strings.Split(preorder, ",")
+	for i, s := range pres {
+		if s == "#" {
+			leaves++
+		} else {
+			node++
+		}
+		if leaves > node+1 {
+			return false
+		}
+		if leaves == node+1 && i < len(pres)-1 {
+			return false
+		}
+	}
+
+	if leaves == node+1 {
+		return true
+	}
+	return false
+}

algorithms/tree/331.isValidSerialization_test.go

@@ -0,0 +1,37 @@
+package tree
+
+import (
+	"testing"
+
+	"Leetcode/algorithms/kit"
+)
+
+// run: go test -v 331.*
+func Test_isValidSerialization(t *testing.T) {
+	cases := []kit.CaseEntry{
+		{
+			Name:     "x1",
+			Input:    "9,3,4,#,#,1,#,#,2,#,6,#,#",
+			Expected: true,
+		},
+		{
+			Name:     "x2",
+			Input:    "1,#",
+			Expected: false,
+		},
+		{
+			Name:     "x3",
+			Input:    "9,#,#,1",
+			Expected: false,
+		},
+		// more test case
+	}
+
+	for _, tt := range cases {
+		t.Run(tt.Name, func(t *testing.T) {
+			if output := isValidSerialization(tt.Input.(string)); output != tt.Expected.(bool) {
+				t.Errorf("isValidSerialization(%s)=%t, expected=%t", tt.Input, output, tt.Expected.(bool))
+			}
+		})
+	}
+}