783. Minimum Distance Between BST Nodes - Easy

前往題目

想法

• 左右子樹和父節點比較就好

思路

這樣的想法問題是孫子可能跟爺爺更近，相較於兒子

1. inorder可以在BST從最小數節點迭代到最大數節點

Code

class Solution {
    int min;
    TreeNode prev;
    public int minDiffInBST(TreeNode root) {
        min = Integer.MAX_VALUE;
        prev = null;
        inorder(root);
        return min;
    }

    private void inorder(TreeNode cur) {
        if (cur == null) return;

        inorder(cur.left);
        // Not in the root node
        if (prev != null) {
            min = Math.min(min, Math.abs(cur.val - prev.val));
        }
        prev = cur;
        inorder(cur.right);
    }
}