Code & Func

第46天。

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

说是水题，就不讲怎么做了，直接上代码吧:

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int maxDepth(TreeNode* root) {
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    return maxDepth(root,0);
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}
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int maxDepth(TreeNode *root,int depth) {
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    if (root == nullptr) return depth;
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    return max(maxDepth(root->left,depth+1),maxDepth(root->right,depth+1));
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}

恩，突然发现好像没必要写的那么长:

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int maxDepth(TreeNode *root) {
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    if (root == nullptr) return 0;
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    return max(maxDepth(root->left),maxDepth(root->right))+1;
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}

恩，送上一个dicuss中BFS的解法：

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int maxDepth(TreeNode *root)
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{
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    if(root == NULL)
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        return 0;
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    int res = 0;
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    queue<TreeNode *> q;
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    q.push(root);
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    while(!q.empty())
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    {
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        ++ res;
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        for(int i = 0, n = q.size(); i < n; ++ i)
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        {
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            TreeNode *p = q.front();
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            q.pop();
10 collapsed lines
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            if(p -> left != NULL)
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                q.push(p -> left);
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            if(p -> right != NULL)
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                q.push(p -> right);
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        }
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    }
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    return res;
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}