【Leetcode】637. Layer average of binary tree

Topic link ： The layer average of a binary tree

Title Description ： Given the root node of a non empty binary tree root , Return the average value of nodes in each layer in the form of array . Differ from the actual answer 10-5 Answers within are acceptable .

analysis ： Find the average value of each layer , Summation Right side view of binary tree The idea is similar . Use breadth first search , Sequence traversal , Find the sum of the node values of each layer divided by the number of nodes in that layer , Record the average .

js The code is as follows ：

//  Use BFS Breadth first search 
 var averageOfLevels = function(root) {
    if (root == null)
        return [0];
    if(root.left==null && root.right==null)
        return [root.val];
    let nodeArray = new Array();
    nodeArray.push(root);
    let valueArray = new Array();
    valueArray.push(root.val);

    while (nodeArray.length!=0) {
        let length=nodeArray.length;
        let i=0,sum=0;
        while(i < length) {
            let left=nodeArray[0].left;
            if(left){
                nodeArray.push(left);
                sum+=left.val;
            }
            let right=nodeArray[0].right;
            if(right){
                nodeArray.push(right);
                sum+=right.val;
            }
            i++;
            nodeArray.shift();
        }
        if(nodeArray.length==0)
            return valueArray;
        valueArray.push(sum/nodeArray.length);
    }
};