algorithm/Week_02/id_140/Leetcode_783_140.java at master · feixiangcode/algorithm · GitHub

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import java.util.ArrayList;

import java.util.List;

/**

* Given a Binary Search Tree (BST) with the root node root, return the minimum difference between the values of any two different nodes in the tree.

* Example :

* Input: root = [4,2,6,1,3,null,null]

* Output: 1

* Explanation:

* Note that root is a TreeNode object, not an array.

* The given tree [4,2,6,1,3,null,null] is represented by the following diagram:

* 4

* / \

* 2 6

* / \

* 1 3

* while the minimum difference in this tree is 1, it occurs between node 1 and node 2, also between node 3 and node 2.

* Note:

* The size of the BST will be between 2 and 100.

* The BST is always valid, each node's value is an integer, and each node's value is different.

public class Leetcode_783_140 {

public int minDiffInBST(TreeNode root) {

List<Integer> res=new ArrayList<Integer>();

inorder(res,root);

int min=Integer.MAX_VALUE;

for(int i=1;i<res.size();i++){

min=Math.min(min,res.get(i)-res.get(i-1));

}

return min;

}

private void inorder(List<Integer> res, TreeNode root){

if(root==null)

return;

inorder(res,root.left);

res.add(root.val);

inorder(res,root.right);

}

class TreeNode {

int val;

TreeNode left;

TreeNode right;

TreeNode(int x) { val = x; }

}

algorithm/Week_02/id_140/Leetcode_783_140.java at master · feixiangcode/algorithm · GitHub

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