117. Populating Next Right Pointers in Each Node II

最新推荐文章于 2021-01-29 16:34:55 发布

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public class Solution {
   public void connect(TreeLinkNode root) {
        if (root == null) return;
        TreeLinkNode pre = root;
        TreeLinkNode cur = root;
        TreeLinkNode lastNode = root;//最后一个节点
        while (true) {
        //这个用来找到第一个有子节点的节点
            int flag = 0;
            TreeLinkNode panduan = pre;
            while (panduan != null) {

                if (panduan.right != null) {
                    flag = 1;
                    cur = panduan;
                    lastNode = panduan;
                    break;
                }
                if (panduan.left != null) {
                    flag = 1;
                    cur = panduan;
                    lastNode = panduan;
                    break;
                }
                panduan = panduan.next;
            }
            if (flag == 0) break;


            while (cur != null) {
                boolean hasLeft = false;
                boolean hasRight = false;

                if (cur.left != null) {
                    hasLeft = true;
                    lastNode = cur.left;
                }
                if (cur.right != null) {
                    hasRight = true;
                    lastNode = cur.right;
                }
                if (hasLeft && hasRight) {
                    cur.left.next = cur.right;
                }
                if (cur.next != null) {
                    if (cur.next.left != null) {
                        lastNode.next = cur.next.left;
                        lastNode = lastNode.next;
                    } else if (cur.next.right != null) {
                        lastNode.next = cur.next.right;
                        lastNode = lastNode.next;
                    }
                }
                cur = cur.next;
            }


            if (panduan.left != null)
                pre = panduan.left;
            else {
                pre = panduan.right;
            }
        }

    }
}