题解 | #二叉搜索树最小差值# | Golang

package main

import (
	"math"
	. "nc_tools"
)

/*
 * type TreeNode struct {
 *   Val int
 *   Left *TreeNode
 *   Right *TreeNode
 * }
 */

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 *
 * @param root TreeNode类
 * @return int整型
 */
func minDifference( root *TreeNode ) int {
    pre_val := -1
    ans := math.MaxInt
    minOrder(root, &pre_val, &ans)
    return ans
}

func minOrder(node *TreeNode, pre_val *int, ans *int) {
    if node == nil {
        return
    }
    minOrder(node.Left, pre_val, ans)
    if *pre_val != -1 {
        *ans = min(*ans, node.Val - *pre_val)
    }
    *pre_val = node.Val
    minOrder(node.Right, pre_val, ans)
}


func abs(a int) int {
    if a < 0 {
        return -a
    }
    return a
}

func min(a int, b int) int {
    if a < b {
        return a
    }
    return b
}