/* * TreeTrans01.h * * Created on: Apr 22, 2016 * Author: lizhen */ #ifndef TREETRANS01_H_ #define TREETRANS01_H_ #include <vector> #include "treeNode.h" #include <stack> using namespace std; class Trans01 { public: // recursion 遍历 //recursion 前序遍历 vector<int> recursionPreT(TreeNode *root) { vector<int> result; recursionPreT(root, result); return result; } void recursionPreT(TreeNode *root, vector<int> &result) { if (root == nullptr) return; if (root != nullptr) result.push_back(root->val); if (root->left != nullptr) recursionPreT(root->left, result); if (root->right != nullptr) recursionPreT(root->right, result); } //recursion 中序遍历 vector<int> recursionInorT(TreeNode *root) { vector<int> result; recursionInorT(root, result); return result; } void recursionInorT(TreeNode *root, vector<int> &result) { if (root == nullptr) return; if (root->left != nullptr) recursionInorT(root->left, result); if (root != nullptr) result.push_back(root->val); if (root->right != nullptr) recursionInorT(root->right, result); } // recursion 后序遍历 vector<int> recursionPostT(TreeNode *root) { vector<int> result; recursionPostT(root, result); return result; } void recursionPostT(TreeNode *root, vector<int> &result) { if (root == nullptr) return; if (root->left != nullptr) recursionPostT(root->left, result); if (root->right != nullptr) recursionPostT(root->right, result); if (root != nullptr) result.push_back(root->val); } //非递归 利用栈 //前序遍历 非递归 利用栈 vector<int> stackPreT(TreeNode *root) { vector<int> result; stack<const TreeNode *> s; if (root != nullptr) s.push(root); while (!s.empty()) { const TreeNode *p = s.top(); s.pop(); result.push_back(p->val); if (p->right != nullptr) s.push(p->right); //栈是后进先出的顺序，所以left后进，left先访问 if (p->left != nullptr) s.push(p->left); } return result; } //中序遍历 非递归 利用栈 vector<int> stackInorT(TreeNode *root) { vector<int> result; stack<const TreeNode *> s; const TreeNode *p = root; while (!s.empty() || p != nullptr) { if (p != nullptr) { s.push(p); p = p->left; } else { p = s.top(); s.pop(); result.push_back(p->val); p = p->right; } } return result; } //后序遍历 非递归 利用栈 vector<int> stackPostT(TreeNode *root) { vector<int> result; stack<const TreeNode *> s; const TreeNode *p, *q; p = root; q = nullptr; //算法： //首先要认识到这是LRN，左节点-右节点-根节点的顺序 //1,找到一个节点左子树，向左下方滑行，直到找到左下方的叶子节点，中间经过的每一个节点都要入s栈 //当栈不为空的时候，出栈p=s.top,pop; // 如果p的右节点不存在或者右节点已经呗访问了，我们就访问当前节点;然后q=p来标记刚刚访问了p节点; // 如果p有右节点&&没有被访问，需要将当前节点p再次入栈s.push(p)，处理p的右节点p=p->right; //实现 //首先找到p的左下方叶子节点 do { while (p != nullptr) { s.push(p); p = p->left; } q = nullptr; while (!s.empty()) { p = s.top(); s.pop(); //判断p节点的右孩子存在？被访问了码？ //这是两个判断，先判断p->right==nullptr,再判断p->right是否已经被访问了 //可以利用一个表达式来完成这一判断 if (p->right == q) { //p没有右孩子， || p的右孩子被访问了 两种情况 result.push_back(p->val); q = p; } else { //p的右孩子没有被访问，p需要再次进栈，后面还会有出栈的动作 s.push(p); p = p->right; break; //------------------再一次找到p的右孩子 } } //while } while (!s.empty()); return result; } //mirros 非递归 //前序遍历 mirros 非递归 //中序遍历 mirros 非递归 //后序遍历 mirros 非递归 }; #endif /* TREETRANS01_H_ */
main函数
/* * main.cpp * * Created on: Apr 7, 2016 * Author: lizhen */ #include <iostream> #include "MySqrt.h" #include <math.h> //#include "findMedianSortedArrays.h" //#include "myfindMedianSortedArrays.h" //#include "longestConsecutive.h" //#include "threeSum.h" //#include "threesumclosest.h" //#include "nextPermutation.h" //#include "trap.h" //#include "rotateImage.h" //#include "setMatrixZeroes.h" //#include "treeNode.h" #include <vector> //#include "preorderT.h" //#include "findMinpathsum.h" #include "TreeTrans01.h" using namespace std; int main(){ TreeNode *root; TreeNode n1(1);TreeNode n2(2);TreeNode n3(3);TreeNode n4(4);TreeNode n5(5); TreeNode n6(6);TreeNode n7(7);TreeNode n8(8);TreeNode n9(9);TreeNode n10(10); TreeNode n11(11);TreeNode n12(12); n1.left = &n2; n1.right = &n3; n2.left = &n4; n2.right = &n5; n3.left = &n6; n3.right = &n7; n4.left = &n8; n4.right = &n9;n6.left = &n10; n7.right = &n11; root = &n1; Trans01 s; vector<int> previt; previt = s.recursionPreT(root); for(auto i:previt){ cout<< i<<" "; }cout<<"\t"<<"recursionPreT"<<endl; //======================== vector<int> invit; invit = s.recursionInorT(root); for(auto i:invit){ cout<<i<<" "; }cout<<"\t"<<"recursionInorT"<<endl; //======================== vector<int> postvit; postvit = s.recursionPostT(root); for(auto i:postvit){ cout<<i<<" "; }cout<<"\t"<<"recursionPostT"<<endl; //##### vector<int> stackPrevit; stackPrevit = s.stackPreT(root); for(auto i: stackPrevit){ cout<<i<<" "; }cout<<"\t"<<"stackPreT"<<endl; //###### vector<int> stackInorvit; stackInorvit = s.stackInorT(root); for(auto i:stackInorvit){ cout<<i<<" "; }cout<<"\t"<<"stackInorT"<<endl; //###### vector<int> stackPostvit; stackPostvit = s.stackPostT(root); for(auto i:stackPostvit){ cout<<i<<" "; }cout<<"\t"<<"stackPostT"<<endl; return 0; }
