1361. Validate Binary Tree Nodes

Difficulty:
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Similar Questions:

    Problem

    You have n binary tree nodes numbered from 0 to n - 1 where node i has two children leftChild[i] and rightChild[i], return true if and only if all the given nodes form exactly one valid binary tree.

    If node i has no left child then leftChild[i] will equal -1, similarly for the right child.

    Note that the nodes have no values and that we only use the node numbers in this problem.

      Example 1:

    Input: n = 4, leftChild = [1,-1,3,-1], rightChild = [2,-1,-1,-1]
    Output: true
    

    Example 2:

    Input: n = 4, leftChild = [1,-1,3,-1], rightChild = [2,3,-1,-1]
    Output: false
    

    Example 3:

    Input: n = 2, leftChild = [1,0], rightChild = [-1,-1]
    Output: false
    

      Constraints:

    Solution

    /**
     * @param {number} n
     * @param {number[]} leftChild
     * @param {number[]} rightChild
     * @return {boolean}
     */
    var validateBinaryTreeNodes = function(n, leftChild, rightChild) {
        var indegree = Array(n).fill(0);
        for (var i = 0; i < n; i++) {
            leftChild[i] !== -1 && indegree[leftChild[i]]++;
            rightChild[i] !== -1 && indegree[rightChild[i]]++;
        }
        var root = indegree.findIndex(num => num === 0);
        var visited = Array(n).fill(false);
        var visit = function(node) {
            if (visited[node]) return false;
            visited[node] = true;
            return (leftChild[node] === -1 || visit(leftChild[node]))
                && (rightChild[node] === -1 || visit(rightChild[node]));
        };
        return visit(root) && visited.every(n => n);
    };
    

    Explain:

    nope.

    Complexity: