LeetCode - Flatten Binary Tree to Linked List

最新推荐文章于 2013-08-22 15:47:19 发布

原创最新推荐文章于 2013-08-22 15:47:19 发布 · 630 阅读

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本文详细介绍了树的前序遍历算法实现，并附带了运行结果展示，包括算法代码、执行时间及通过的测试案例数量。

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树的前序遍历算法：

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public void flatten(TreeNode root) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if (root == null)
            return;
        TreeNode previous = root;
        Stack<TreeNode> stack = new Stack<TreeNode>();
        if (root.right != null) stack.push(root.right);
        if (root.left != null) stack.push(root.left);
        
        while (!stack.empty()) {
            TreeNode current = stack.pop();
            previous.left = previous.right = null;
            previous.right = current;
            previous = current;
            if (current.right != null) stack.push(current.right);
            while (current.left != null) {
                current = current.left;
                previous.left = previous.right = null;
                previous.right = current;
                previous = current;
                if (current.right != null) stack.push(current.right);
            }
        }
    }
}

运行结果：

Run Status: Accepted!

Program Runtime: 684 milli secs

Progress: 225/225 test
 cases passed.