Problem Minimum Depth of Binary Tree

Problem Description:

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.

Solution:

    public int minDepth(TreeNode root) {
        if (root == null) return 0;
        int left = minDepth(root.left);
        int right = minDepth(root.right);
        return 1 + (left == 0 ? right : (right == 0 ? left : Math.min(left, right)));
    }