## ● 二叉树层序遍历

### 参考回答：

```function tree(obj) {
var obj = obj.split(')');
obj.pop();
var newobj = [];
for (var i = 0; i < obj.length; i++) {
newobj.push(obj[i].replace('(',''));
}
var root = {
value: null, left: null, right: null,have:0
}
var u;
for(var i = 0; i < newobj.length; i++) {
var a1 = newobj[i].split(',')[0];
var a2 = newobj[i].split(',')[1];
u = root;
if(a2!==''){
for (var j = 0;j<a2.length;j++) {
if(a2[j]==='L'){
if(u.left === null){
u.left = newnode();
u = u.left;
}else {
u = u.left;
}
} else if(a2[j]==='R') {
if(u.right === null){
u.right = newnode();
u = u.right;
}else{
u = u.right;
}
}
}
if(u.have === 1)  {
} else{
u.value = a1;
u.have = 1;
}
}else {
root.value = a1;
u.have = 1;
}
}
return root;
}```

//建立新结点

```function newnode() {
return {value: null, left: null, right: null,have:0};
}```

//队列遍历

```function bfs() {
var root = tree('(11,LL)(7,LLL)(8,R)(5,)(4,L)(13,RL)(2,LLR)(1,RRR)(4,RR)');
var front = 0,rear = 1,n=0;
var q = [],ans=[];
q[0] = root;
while(front < rear) {
var u = q[front++];
if(u.have!==1) {
return;
}
ans[n++] = u.value;
if(u.left!==null) {
q[rear++] = u.left;
}
if(u.right!==null) {
q[rear++] = u.right;
}
}
console.log(ans.join(' '));
}
bfs();```

B树和B+树的区别：