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试设计判断两棵二叉树是否相似的算法。所谓二叉树T1和T2相似，指的是T1和T2都是空的二叉树或都只有一个根节点；或者T1的左子树和T2的左子树是相似的，且T1的右子树和T2的右子树是相似的

#include <iostream>
#include <stack>
#include <queue>
typedef struct treenode{char data;struct treenode *left;struct treenode *right;
}treenode,*ptreenode;ptreenode buytreenode(char x)
{ptreenode n=(ptreenode) malloc(sizeof (treenode));n->data=x;n->left= nullptr,n->right= nullptr;return n;
}
ptreenode build_tree1()
{ptreenode root= buytreenode('A');root->left= buytreenode('B');root->right= buytreenode('C');root->left->left= buytreenode('D');root->left->right= buytreenode('E');root->right->left= buytreenode('F');root->right->right= buytreenode('G');root->left->left->left= buytreenode('H');root->left->left->right= buytreenode('I');return root;
}ptreenode build_tree2()
{ptreenode root= buytreenode('A');root->left= buytreenode('B');root->right= buytreenode('C');root->left->left= buytreenode('D');root->left->right= buytreenode('E');root->right->left= buytreenode('F');root->right->right= buytreenode('G');root->left->left->left= buytreenode('H');root->left->left->right= buytreenode('I');root->left->right->left= buytreenode('J');root->left->right->right= buytreenode('K');root->right->left->left= buytreenode('L');root->right->left->right= buytreenode('M');root->right->right->left= buytreenode('N');root->right->right->right= buytreenode('O');return root;
}ptreenode build_tree3()
{ptreenode root= buytreenode('Z');root->left= buytreenode('Y');root->right= buytreenode('W');root->left->left= buytreenode('X');root->left->right= buytreenode('E');root->right->left= buytreenode('F');root->right->right= buytreenode('G');root->left->left->left= buytreenode('H');root->left->left->right= buytreenode('I');root->left->right->left= buytreenode('J');root->left->right->right= buytreenode('K');root->right->left->left= buytreenode('L');root->right->left->right= buytreenode('M');root->right->right->left= buytreenode('N');root->right->right->right= buytreenode('O');return root;
}
void print_tree(ptreenode root) {std::queue<ptreenode> tmp;tmp.push(root);int s = tmp.size();while (!tmp.empty()) {ptreenode t = tmp.front();tmp.pop();s--;printf("%3c", t->data);if (t->left) tmp.push(t->left);if (t->right) tmp.push(t->right);if (s == 0) puts(""), s = tmp.size();}
}bool isSimilar(ptreenode root1,ptreenode root2)
{if(root1== nullptr&&root2== nullptr) return true;if(root1== nullptr||root2== nullptr) return false;return isSimilar(root1->left,root2->left)&& isSimilar(root1->right,root2->right);
}
int main() {ptreenode root1=build_tree1();ptreenode root2=build_tree2();ptreenode root3=build_tree3();printf("tree1:\n");print_tree(root1);printf("tree2:\n");print_tree(root2);printf("tree3:\n");print_tree(root3);if(isSimilar(root1,root2)) printf("tree1 and tree2 are similar");else printf("tree1 and tree2 are different\n");if(isSimilar(root2,root3)) printf("tree2 and tree3 are similar");else printf("tree2 and tree3 are different");return 0;
}