minimumDepthofBinaryTree.js

//////////////////////////////////////////////Minimum Depth of Binary Tree/////////////////////////////////////////////////
// Given a binary tree, find its minimum depth.
// The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.
// Note: A leaf is a node with no children.
// Example 1:
//
// Input: root = [3,9,20,null,null,15,7]
// Output: 2
// Example 2:
//
// Input: root = [2,null,3,null,4,null,5,null,6]
// Output: 5
const minDepth = function(root) {
    if (root == null) return 0;
    if (root.left == null && root.right == null) return 1;

    let leftD = minDepth(root.left);
    let rightD = minDepth(root.right);

    if (root.left == null && root.right != null) return rightD + 1;
    if (root.right == null && root.left != null) return leftD + 1;

    return Math.min(leftD, rightD) + 1;
};

// console.log(minDepth([3,9,20,null,null,15,7]));
// console.log(minDepth([2,null,3,null,4,null,5,null,6]));