标签:style blog http color os art
给定一颗二叉树,和两个给定的结点,求出这两个结点之间的距离
拿到题目时不要认为是求出二叉树的结点之间的最大距离,题目是求两个结点的之间的距离
题目有几种情况
本题的解题思路是
利用层次遍历的方法,获取每个结点的高度,根节点左子树的高度用正数表示,根节点右子树的高度用负数表示
这样当两个结点分布在:一个结点分布在根节点的左子树,一个结点分布在根节点的右子树时,只需要两个结点的高度的差得绝对值即可
如果一个结点是另一个结点的祖先结点,只需要高度大的结点顺着祖先结点找到高度小得结点,如果到达相同的高度结点不相同说明是兄弟结点关系
#include <iostream> #include <vector> #include <queue> #include <stack> #include <string> #include <algorithm> using namespace std; struct TreeNode{ int val; TreeNode* left; TreeNode* right; TreeNode(int val_ = 0):val(val_),left(NULL),right(NULL){} }; struct TreeHeightNode{ int height; TreeNode* node; TreeHeightNode* parent; TreeHeightNode(TreeNode* node_ = NULL,int height_ = 0,TreeHeightNode* parent_ =NULL): node(node_), height(height_),parent(parent_){} }; int getDistanceBetweenNode(TreeNode* root,TreeNode* a, TreeNode* b){ if(root == NULL ) return -1; queue<TreeHeightNode *> que; que.push(new TreeHeightNode(root,0)); bool flagA = false, flagB = false; // int heightA = 0, heightB = 0; TreeHeightNode* heightA =NULL, *heightB = NULL; while(!que.empty()){ TreeHeightNode* tmp = que.front(); que.pop(); TreeNode *node = tmp->node; if(node == a) {flagA = true;heightA = tmp;} if(node == b) {flagB = true;heightB = tmp;} if(flagA && flagB) break; if(node->left){ if(node->val == 0) que.push(new TreeHeightNode(node->left,1,tmp)); else if(node->val > 0) que.push(new TreeHeightNode(node->left,tmp->height+1,tmp)); else if(node->val < 0) que.push(new TreeHeightNode(node->left,tmp->height-1,tmp)); } if(node->right){ if(node->val == 0) que.push(new TreeHeightNode(node->right,-1,tmp)); else if(node->val > 0) que.push(new TreeHeightNode(node->right,tmp->height+1,tmp)); else if(node->val < 0) que.push(new TreeHeightNode(node->right,tmp->height-1,tmp)); } } if(!flagA || !flagB) return -1; else{ int ha = heightA->height, hb =heightB->height; if(ha*hb <=0) return ha-hb; else{ if((ha >= hb && hb > 0) || (ha < hb && hb < 0)){ int cnt = ha-hb; while(cnt-->0){ heightA=heightA->parent; } if(heightA == heightB) return ha-hb; else return ha-hb+2; }else{ int cnt = hb - ha; while(cnt-- > 0){ heightB=heightB->parent; } if(heightB == heightA) return hb-ha; else return hb-ha+2; } } } } int main(){ TreeNode *root = new TreeNode(1); TreeNode *left = new TreeNode(2); TreeNode *right = new TreeNode(3); root->left = left; root->right = right; TreeNode *left1 = new TreeNode(4); TreeNode *right1 = new TreeNode(5); left->left = left1; left->right = right1; TreeNode *left2 = new TreeNode(4); TreeNode *right2 = new TreeNode(5); left1->left = left2; left1->right = right2; cout<<getDistanceBetweenNode(root,left2,right)<<endl; return 0; }
其实寻找两个结点的距离就是求两个结点的公共祖先结点,所以另一种方法是找到o最小其公共祖先结点
然后
求二叉树的给定两个结点之间的距离,布布扣,bubuko.com
标签:style blog http color os art
原文地址:http://www.cnblogs.com/xiongqiangcs/p/3820761.html