題目
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.
答題
采用中序排序后，就可以得到一個排序好的數(shù)組，最小值肯定是數(shù)組相鄰兩個值之差捐寥。
private int minDis = -1;
public int minDiffInBST(TreeNode root) {
List<Integer> list = new ArrayList<Integer>();
print(root, list);
int size = list.size();
for (int i = 0; i < size - 1; i++) {
int val = Math.abs(list.get(i) - list.get(i + 1));
minDis = (minDis == -1) ? val : Math.min(val, minDis);
}
return minDis;
}
public void print(TreeNode node, List<Integer> list) {
if (node == null) {
return;
}
print(node.left, list);
list.add(node.val);
print(node.right, list);
}
