二叉树总结

 https://blog.csdn.net/luckyxiaoqiang/article/details/7518888

struct TreeNode {
    int val;
    TreeNode* left;
    TreeNode* right;
};

1、求二叉树中节点的个数

int getTreeNodeNum(TreeNode* root) {
    if (root == NULL)
        return 0;
    return getTreeNodeNum(root->left) + getTreeNodeNum(root->right) + 1;
}

2、求二叉树的深度

int getTreeDepth(TreeNode* root) {
    if(root == NULL)
        return 0;
    int leftDepth = getTreeDepth(root->left);
    int rightDepth = getTreeDepth(root->right);
    return leftDepth > rightDepth ? (leftDepth + 1) : (rightDepth + 1);
}

 3、二叉树的前序遍历

void preTreeNode(TreeNode* root) {
    if (root == NULL)
        return;
    cout << root->val << endl;
    preTreeNode(root->left);
    preTreeNode(root->right);
}

4、求二叉树叶子节点的个数

int getLeafNodeNum(TreeNode* root) {
    if (root == NULL)
        return 0;
    if (root->left == NULL && root->right == NULL)
        return 1;
    return getLeafNodeNum(root->left) + getLeafNodeNum(root->right);
}