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Solution.java
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53 lines (49 loc) · 1.67 KB
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package leetCode_530;
/**
* @author dimdark
* @date 2017-09-21
* @time 10:27 AM
*/
public class Solution {
public class TreeNode {
int val;
TreeNode left, right;
TreeNode(int x) {
this.val = x;
}
}
public int getMinimumDifference(TreeNode root) {
if (root == null) return -1; //not calculate
if (root.left == null && root.right == null) return -1; // not calculate
int preValue = -1, currValue, minAbsValue = Integer.MAX_VALUE;
TreeNode node = root, predecessor;
while (node != null) { // mirros traverse
if (node.left == null) {
currValue = node.val;
if (preValue != -1) {
minAbsValue = Math.min(minAbsValue, Math.abs(currValue - preValue));
}
preValue = currValue;
node = node.right;
} else {
predecessor = node.left;
while (predecessor.right != node && predecessor.right != null) {
predecessor = predecessor.right;
}
if (predecessor.right != null) { // delete link
predecessor.right = null;
currValue = node.val;
if (preValue != -1) {
minAbsValue = Math.min(minAbsValue, Math.abs(currValue - preValue));
}
preValue = currValue;
node = node.right;
} else { // set link
predecessor.right = node;
node = node.left;
}
}
}
return minAbsValue;
}
}