[算法相關] Minimum Depth of Binary Tree

111. Minimum Depth of Binary Tree

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

如題，給定一個二叉樹確定其最小深度。

               

圖示二叉樹的最小深度爲三。代碼如下：

 

public class Solution {
public int minDepth(TreeNode root) {
    if (root == null)
        return 0;
    int depth = 1;
    Queue<TreeNode> queue = new LinkedList<TreeNode>();
    TreeNode temp,magic = new TreeNode(0);
    queue.add(root);
    queue.add(magic);
    while(!queue.isEmpty()){
        temp = queue.poll();
        if(temp.equals(magic)){
            if(!queue.isEmpty()){
                depth++;
                queue.add(magic);
            }
            continue;
        }
        if(temp.left == null && temp.right == null)
            return depth;
        if(temp.left != null)
            queue.add(temp.left);
        if(temp.right != null)
            queue.add(temp.right);
    }
    return depth;
}
}

上述程序使用了層次遍歷的方法，運用了遍歷操作。不理解，這裏的層次遍歷是如何用的，並且二叉樹是如何與隊列相聯繫的。

 

To be  continue……