LeetCode:Maximum Depth of Binary Tree
2015-02-07 12:47
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转载自 http://www.cnblogs.com/bakari/p/4126693.html
要求:求二叉树的深度(二叉树的深度为最远叶子节点到根节点的距离,即根节点到最远叶子节点的距离)
有两种求解的思路,一种采用DFS的思想,一种采用BFS的思想,如下代码所示:
struct TreeNode {
int val;
TreeNode* left;
TreeNode* right;
TreeNode(int x): val(x), left(NULL),right(NULL) {}
};
//采用DFS的思想
int maxDepth(TreeNode *root)
{
if (NULL == root)
return 0;
int l = maxDepth(root->left);
int r = maxDepth(root->right);
return l > r ? l + 1:r+1;
//以上这两种方式有一种更简便的方法
//return 1 + max(maxDepth(root->left), maxDepth(root->right));
}
//采用BFS的方法,引入队列
int maxDepth(TreeNode *root)
{
if (NULL == root)
return 0;
queue <TreeNode *> que;
int nCount = 1;
int nDepth = 0;// 记录队列里面每一层上的元素
que.push(root);
while(!que.empty()) {
TreeNode *pTemp = que.front();
que.pop();
nCount --;
if (pTemp->left)
que.push(pTemp->left);
if (pTemp->right)
que.push(pTemp->right);
if (nCount == 0) {
nDepth ++;
nCount = que.size();
}
}
return nDepth;
}
要求:求二叉树的深度(二叉树的深度为最远叶子节点到根节点的距离,即根节点到最远叶子节点的距离)
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.
有两种求解的思路,一种采用DFS的思想,一种采用BFS的思想,如下代码所示:
struct TreeNode {
int val;
TreeNode* left;
TreeNode* right;
TreeNode(int x): val(x), left(NULL),right(NULL) {}
};
//采用DFS的思想
int maxDepth(TreeNode *root)
{
if (NULL == root)
return 0;
int l = maxDepth(root->left);
int r = maxDepth(root->right);
return l > r ? l + 1:r+1;
//以上这两种方式有一种更简便的方法
//return 1 + max(maxDepth(root->left), maxDepth(root->right));
}
//采用BFS的方法,引入队列
int maxDepth(TreeNode *root)
{
if (NULL == root)
return 0;
queue <TreeNode *> que;
int nCount = 1;
int nDepth = 0;// 记录队列里面每一层上的元素
que.push(root);
while(!que.empty()) {
TreeNode *pTemp = que.front();
que.pop();
nCount --;
if (pTemp->left)
que.push(pTemp->left);
if (pTemp->right)
que.push(pTemp->right);
if (nCount == 0) {
nDepth ++;
nCount = que.size();
}
}
return nDepth;
}
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