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PopulatingNextRightPointers.java
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PopulatingNextRightPointers.java
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import java.util.ArrayDeque;
import java.util.Deque;
/**
* 116. 117. Populating Next Right Pointers in Each Node
* 层序遍历
* @author LBW
*/
public class PopulatingNextRightPointers {
public Node connect(Node root) {
Deque<Node> queue = new ArrayDeque<>();
if (root != null)
queue.offer(root);
while (!queue.isEmpty()) {
int size = queue.size();
for (int i = 0; i < size; i++) {
Node cur = queue.poll();
if (cur.left != null)
queue.offer(cur.left);
if (cur.right != null)
queue.offer(cur.right);
if (i < size - 1)
cur.next = queue.peek();
else
cur.next = null; //the last element in the level.
}
}
return root;
}
}
class Node {
public int val;
public Node left;
public Node right;
public Node next;
public Node() {}
public Node(int _val) {
val = _val;
}
public Node(int _val, Node _left, Node _right, Node _next) {
val = _val;
left = _left;
right = _right;
next = _next;
}
}