// 面试题32(二):分行从上到下打印二叉树 // 题目:从上到下按层打印二叉树,同一层的结点按从左到右的顺序打印,每一层 // 打印到一行。 #include <cstdio> #include "BinaryTree.h" #include <queue> void Print(BinaryTreeNode* pRoot) { if (pRoot == nullptr) return; std::deque<BinaryTreeNode*> dequeTreeNode; dequeTreeNode.push_back(pRoot); int nextLevel = 0; //下一层中需要打印的次数 int toBePrinted = 1; //当前层需要打印的次数 while (!dequeTreeNode.empty()) { BinaryTreeNode* pNode = dequeTreeNode.front(); dequeTreeNode.pop_front(); printf("%d ", pNode->m_nValue); if (pNode->m_pLeft) { dequeTreeNode.push_back(pNode->m_pLeft); ++nextLevel; } if (pNode->m_pRight) { dequeTreeNode.push_back(pNode->m_pRight); ++nextLevel; } --toBePrinted; //打印次数-1 if (toBePrinted == 0) //当前层打印完成, 重置数据 { toBePrinted = nextLevel; nextLevel = 0; printf("\n"); } } }
// ====================测试代码==================== // 8 // 6 10 // 5 7 9 11 void Test1() { BinaryTreeNode* pNode8 = CreateBinaryTreeNode(8); BinaryTreeNode* pNode6 = CreateBinaryTreeNode(6); BinaryTreeNode* pNode10 = CreateBinaryTreeNode(10); BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5); BinaryTreeNode* pNode7 = CreateBinaryTreeNode(7); BinaryTreeNode* pNode9 = CreateBinaryTreeNode(9); BinaryTreeNode* pNode11 = CreateBinaryTreeNode(11); ConnectTreeNodes(pNode8, pNode6, pNode10); ConnectTreeNodes(pNode6, pNode5, pNode7); ConnectTreeNodes(pNode10, pNode9, pNode11); printf("====Test1 Begins: ====\n"); printf("Expected Result is:\n"); printf("8 \n"); printf("6 10 \n"); printf("5 7 9 11 \n\n"); printf("Actual Result is: \n"); Print(pNode8); printf("\n"); DestroyTree(pNode8); } // 5 // 4 // 3 // 2 void Test2() { BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5); BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4); BinaryTreeNode* pNode3 = CreateBinaryTreeNode(3); BinaryTreeNode* pNode2 = CreateBinaryTreeNode(2); ConnectTreeNodes(pNode5, pNode4, nullptr); ConnectTreeNodes(pNode4, pNode3, nullptr); ConnectTreeNodes(pNode3, pNode2, nullptr); printf("====Test2 Begins: ====\n"); printf("Expected Result is:\n"); printf("5 \n"); printf("4 \n"); printf("3 \n"); printf("2 \n\n"); printf("Actual Result is: \n"); Print(pNode5); printf("\n"); DestroyTree(pNode5); } // 5 // 4 // 3 // 2 void Test3() { BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5); BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4); BinaryTreeNode* pNode3 = CreateBinaryTreeNode(3); BinaryTreeNode* pNode2 = CreateBinaryTreeNode(2); ConnectTreeNodes(pNode5, nullptr, pNode4); ConnectTreeNodes(pNode4, nullptr, pNode3); ConnectTreeNodes(pNode3, nullptr, pNode2); printf("====Test3 Begins: ====\n"); printf("Expected Result is:\n"); printf("5 \n"); printf("4 \n"); printf("3 \n"); printf("2 \n\n"); printf("Actual Result is: \n"); Print(pNode5); printf("\n"); DestroyTree(pNode5); } void Test4() { BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5); printf("====Test4 Begins: ====\n"); printf("Expected Result is:\n"); printf("5 \n\n"); printf("Actual Result is: \n"); Print(pNode5); printf("\n"); DestroyTree(pNode5); } void Test5() { printf("====Test5 Begins: ====\n"); printf("Expected Result is:\n"); printf("Actual Result is: \n"); Print(nullptr); printf("\n"); } // 100 // / // 50 // \ // 150 void Test6() { BinaryTreeNode* pNode100 = CreateBinaryTreeNode(100); BinaryTreeNode* pNode50 = CreateBinaryTreeNode(50); BinaryTreeNode* pNode150 = CreateBinaryTreeNode(150); ConnectTreeNodes(pNode100, pNode50, nullptr); ConnectTreeNodes(pNode50, nullptr, pNode150); printf("====Test6 Begins: ====\n"); printf("Expected Result is:\n"); printf("100 \n"); printf("50 \n"); printf("150 \n\n"); printf("Actual Result is: \n"); Print(pNode100); printf("\n"); } int main(int argc, char* argv[]) { Test1(); Test2(); Test3(); Test4(); Test5(); Test6(); return 0; }
分析:额外设置标志位来控制回车。