0222完全二叉树的节点个数JavaScript版本

This commit is contained in:
xll
2021-05-25 20:25:27 +08:00
parent fe0abe75fd
commit 8c412007c8

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@ -243,6 +243,74 @@ Python
Go
JavaScript:
递归版本
```javascript
var countNodes = function(root) {
//递归法计算二叉树节点数
// 1. 确定递归函数参数
const getNodeSum=function(node){
//2. 确定终止条件
if(node===null){
return 0;
}
//3. 确定单层递归逻辑
let leftNum=getNodeSum(node.left);
let rightNum=getNodeSum(node.right);
return leftNum+rightNum+1;
}
return getNodeSum(root);
};
```
迭代(层序遍历)版本
```javascript
var countNodes = function(root) {
//层序遍历
let queue=[];
if(root===null){
return 0;
}
queue.push(root);
let nodeNums=0;
while(queue.length){
let length=queue.length;
while(length--){
let node=queue.shift();
nodeNums++;
node.left&&queue.push(node.left);
node.right&&queue.push(node.right);
}
}
return nodeNums;
};
```
利用完全二叉树性质
```javascript
var countNodes = function(root) {
//利用完全二叉树的特点
if(root===null){
return 0;
}
let left=root.left;
let right=root.right;
let leftHeight=0,rightHeight=0;
while(left){
left=left.left;
leftHeight++;
}
while(right){
right=right.right;
rightHeight++;
}
if(leftHeight==rightHeight){
return Math.pow(2,leftHeight+1)-1;
}
return countNodes(root.left)+countNodes(root.right)+1;
};
```