110. 平衡二叉树

package main
import (
    "fmt"
    "math"
)
type TreeNode struct {
         Val int
         Left *TreeNode
         Right *TreeNode
     }
func isBalanced(root *TreeNode) bool {
    if root ==nil {
        return true
    }
    l := dfs(root.Left)
    r := dfs(root.Right)
    return math.Abs(float64(l)-float64(r)) <=1&&isBalanced(root.Right)&&isBalanced(root.Left)
}
func dfs(root *TreeNode)int{
    if root ==nil {
        return 0
    }
    return max(dfs(root.Left),dfs(root.Right))+1
}
func max(a ,b int)int{
    if a>b {
        return a
    }
    return b
}
func main() {
    a := &TreeNode{
        Val: 3,
    }
    b := &TreeNode{
        Val: 9,
    }
    a.Left = b
    c := &TreeNode{
        Val: 20,
    }
    a.Right = c
    d := &TreeNode{
        Val: 15,
    }
    c.Left = d
    e := &TreeNode{
        Val: 7,
    }
    c.Right = e
    fmt.Println(isBalanced(a))
    // 4,2,5,1,6,3
    a1 := &TreeNode{
        Val: 1,
    }
    b1 := &TreeNode{
        Val: 2,
    }
    a1.Left = b1
    c1 := &TreeNode{
        Val: 2,
    }
    a1.Right = c1
    d1 := &TreeNode{
        Val: 3,
    }
    c1.Left = d1
    e1 := &TreeNode{
        Val: 3,
    }
    c1.Right = e1
    f1 := &TreeNode{
        Val: 4,
    }
    e1.Left = f1
    g1 := &TreeNode{
        Val: 4,
    }
    e1.Right = g1
    fmt.Println(isBalanced(a1))
}