1、利用遞歸的方式獲取樹的前序遍歷結(jié)果
//獲取樹的前序遍歷
public static String preTraver(TreeNode root){
if (root!=null) {
re += root.val;
if (root.left != null)
preTraver(root.left);
if (root.right != null)
preTraver(root.right);
}
return re;
}
2琅束、 利用遞歸的方式獲取樹的中序遍歷結(jié)果
//獲取樹的中序遍歷
public static String medTraver(TreeNode root){
if (root!=null) {
if (root.left != null)
medTraver(root.left);
re += root.val;
if (root.right != null)
medTraver(root.right);
}
return re;
}
3诈嘿、利用遞歸的方式獲取樹的后序遍歷結(jié)果
//獲取樹的后序遍歷
public static String aftTraver(TreeNode root){
if (root!=null) {
if (root.left != null)
preTraver(root.left);
if (root.right != null)
preTraver(root.right);
re += root.val;
}
return re;
}
4、利用隊列實現(xiàn)層次遍歷
//獲取樹的層次遍歷
public static String levelTraver(TreeNode root){
Queue<TreeNode> queue = new ArrayDeque<TreeNode>();
TreeNode node;
if (root!=null)
queue.offer(root);
while (!queue.isEmpty()){
node=queue.poll();
re+=node.val;
if (node.left!=null)
queue.offer(node.left);
if (node.right!=null)
queue.offer(node.right);
}
return re;
}
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