symmetric_tree.go

package main

// Definition for a binary tree node.
typeTreeNodestruct {
Valint
Left*TreeNode
Right*TreeNode
}

varanswerbool

// Recursive
funcisSymmetrics(root*TreeNode) bool {

// Runtime: 3 ms, faster than 70.37% of Go online submissions for Symmetric Tree.
// Memory Usage: 2.9 MB, less than 83.92% of Go online submissions for Symmetric Tree.
varanswerbool=true
ifroot!=nil {
findSymmetricity(root.Left, root.Right)
 }
returnanswer
}

funcfindSymmetricity(firstNode, secondNode*TreeNode) {
iffirstNode==nil&&secondNode==nil||answer==false {
return
 }
iffirstNode==nil||secondNode==nil||firstNode.Val!=secondNode.Val {
answer=false
return
 }
findSymmetricity(firstNode.Left, secondNode.Right)
findSymmetricity(firstNode.Right, secondNode.Left)
}

funcisSymmetric(root*TreeNode) bool {

// Runtime: 0 ms, faster than 100.00% of Go online submissions for Symmetric Tree.
// Memory Usage: 2.9 MB, less than 19.79% of Go online submissions for Symmetric Tree.
ifroot==nil {
returntrue
 }

stack:=make([]*TreeNode, 2)
stack[0] =root
stack[1] =root

forlen(stack) >0 {
n:=len(stack) -1
firstNode:=stack[n]
// rewrite
stack=stack[:n]

n=len(stack) -1
secondNode:=stack[n]
stack=stack[:n]

iffirstNode==nil&&secondNode==nil {
continue
 }

iffirstNode==nil||secondNode==nil {
returnfalse
 }

iffirstNode.Val!=secondNode.Val {
returnfalse
 }

stack=append(stack, firstNode.Left)
stack=append(stack, secondNode.Right)
stack=append(stack, firstNode.Right)
stack=append(stack, secondNode.Left)
 }

returntrue
}