111. Minimum Depth of Binary Tre

https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/

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（图片来源https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/

）

日期	是否一次通过	comment
2020-03-15	0

NOTE: [1,2] ，返回2

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递归

public int minDepth(TreeNode root) {
        if(root == null) {
            return 0;
        }

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

        // 防止corner case: [1,2], 返回应该是2，而不是1，所以需要leftD+rightD+1
        return (leftD == 0 || rightD == 0) ? leftD+rightD+1 : Math.min(leftD, rightD) + 1;
    }