Minimum Depth of Binary Tree【leetcode】

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.

递归。

考虑5种情况，

1.节点为空

2.节点不为空，且左右儿子节点也不为空

3，右儿子节点为空

4，左儿子节点为空

5，左右儿子都为空

int minDepth(TreeNode *root) {
	if (root == NULL)
		return 0;
	int a=0, b=0;
	if (root->left &&root->right){
		a = minDepth(root->left) + 1;
		b = minDepth(root->right) + 1;
		return a < b ? a : b;
	}else
	if (root->left && root->right==NULL){
		return 1 + minDepth(root->left);
	}else
	if (root->right && root->left==NULL){
		return 1 + minDepth(root->right);
	}else
	if (root->left == NULL && root->right == NULL){
		return 1;
	}

}