LeetCode-the K-th largest node of the binary search tree

Title description

Problem-solving ideas

• First build a collection to store all the elements traversed.
• Use DFS to traverse the binary tree and store the result in the collection.
• Convert collection to array
• Sort in descending order by the sort method
• The element with subscript [k-1] of the sorted array is the K-th largest element of the binary search tree

Implementation code

var kthLargest = function(root, k) {
    
    

    const set = new Set();
    const dfs = function(node) {
    
    
        if (node === null) {
    
    
            return;
        }

        set.add(node.val);
        dfs(node.left);
        dfs(node.right);
    }
    dfs(root);
    const arr = [...set];
    arr.sort((a,b) => {
    
    
        return b-a;
    });

    return arr[k-1];

};