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Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.
According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w as descendants (where we allow a node to be a descendant of itself).”
_______3______
/ ___5__ ___1__
/ \ / 6 _2 0 8
/ 7 4
For example, the lowest common ancestor (LCA) of nodes 5 and 1 is 3. Another example is LCA of nodes 5 and 4 is 5, since a node can be a descendant of itself according to the LCA definition.
#include<iostream>
using namespace std;
struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
TreeNode* L=NULL;
int digui(TreeNode* root,TreeNode* p,TreeNode* q)
{
if(root->left==NULL&&root->right==NULL)
{
if(root==p||root==q)
return 1;
else
return 0;
}
int left=0,right=0;
if(root->left!=NULL)
left=digui(root->left,p,q);
if(root->right!=NULL)
right=digui(root->right,p,q);
if(left+right==0)
{
if(root==p||root==q)
return 1;
else
return 0;
}
else if(left+right==1)
{
if(root==p||root==q)
{
L=root;
return 0;
}
else
return 1;
}
else
{
L=root;
return 0;
}
}
TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
digui(root,p,q);
return L;
}
int main()
{
}
leetcode_236——Lowest Common Ancestor of a Binary Tree（tree，后序遍历）
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原文地址：http://www.cnblogs.com/yanliang12138/p/4658140.html
