JZ-C-25

剑指offer第二十五题：二叉树中和为某一值的路径

//============================================================================
// Name        : JZ-C-25.cpp
// Author      : Laughing_Lz
// Version     :
// Copyright   : All Right Reserved
// Description : 二叉树中和为某一值的路径
//============================================================================

#include <iostream>
#include <stdio.h>
#include "BinaryTree.h"
#include <vector>

using namespace std;

void FindPath(BinaryTreeNode* pRoot, int expectedSum, std::vector<int>& path,
        int& currentSum); //函数声明

void FindPath(BinaryTreeNode* pRoot, int expectedSum) {
    if (pRoot == NULL) {
        return;
    }
    std::vector<int> path;
    int currentSum = 0; //当前路径值和
    FindPath(pRoot, expectedSum, path, currentSum);
}
void FindPath(BinaryTreeNode* pRoot, int expectedSum, std::vector<int>& path,
        int& currentSum) {
    currentSum += pRoot->m_nValue;
    path.push_back(pRoot->m_nValue);
    // 如果是叶结点，并且路径上结点的和等于输入的值
    // 打印出这条路径
    bool isLeaf = pRoot->m_pLeft == NULL && pRoot->m_pRight == NULL;
    if (isLeaf && currentSum == expectedSum) {
        printf("A path is found: ");
        std::vector<int>::iterator it = path.begin();
        for (; it != path.end(); it++) {
            printf("%d\t", *it);
        }
        printf("\n");
    }
    // 如果不是叶结点，则遍历它的子结点
    if (pRoot->m_pLeft != NULL)
        FindPath(pRoot->m_pLeft, expectedSum, path, currentSum);
    if (pRoot->m_pRight != NULL)
        FindPath(pRoot->m_pRight, expectedSum, path, currentSum);

    // 在返回到父结点之前，在路径上删除当前结点，
    // 并在currentSum中减去当前结点的值 ★★
    currentSum -= pRoot->m_nValue;
    path.pop_back();

}
// ====================测试代码====================
void Test(char* testName, BinaryTreeNode* pRoot, int expectedSum) {
    if (testName != NULL)
        printf("%s begins:\n", testName);

    FindPath(pRoot, expectedSum);

    printf("\n");
}

//            10
//         /      \
//        5        12
//       /\
//      4  7
// 有两条路径上的结点和为22
void Test1() {
    BinaryTreeNode* pNode10 = CreateBinaryTreeNode(10);
    BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);
    BinaryTreeNode* pNode12 = CreateBinaryTreeNode(12);
    BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4);
    BinaryTreeNode* pNode7 = CreateBinaryTreeNode(7);

    ConnectTreeNodes(pNode10, pNode5, pNode12);
    ConnectTreeNodes(pNode5, pNode4, pNode7);

    printf("Two paths should be found in Test1.\n");
    Test("Test1", pNode10, 22);

    DestroyTree(pNode10);
}

//            10
//         /      \
//        5        12
//       /\
//      4  7
// 没有路径上的结点和为15
void Test2() {
    BinaryTreeNode* pNode10 = CreateBinaryTreeNode(10);
    BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);
    BinaryTreeNode* pNode12 = CreateBinaryTreeNode(12);
    BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4);
    BinaryTreeNode* pNode7 = CreateBinaryTreeNode(7);

    ConnectTreeNodes(pNode10, pNode5, pNode12);
    ConnectTreeNodes(pNode5, pNode4, pNode7);

    printf("No paths should be found in Test2.\n");
    Test("Test2", pNode10, 15);

    DestroyTree(pNode10);
}

//               5
//              /
//             4
//            /
//           3
//          /
//         2
//        /
//       1
// 有一条路径上面的结点和为15
void Test3() {
    BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);
    BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4);
    BinaryTreeNode* pNode3 = CreateBinaryTreeNode(3);
    BinaryTreeNode* pNode2 = CreateBinaryTreeNode(2);
    BinaryTreeNode* pNode1 = CreateBinaryTreeNode(1);

    ConnectTreeNodes(pNode5, pNode4, NULL);
    ConnectTreeNodes(pNode4, pNode3, NULL);
    ConnectTreeNodes(pNode3, pNode2, NULL);
    ConnectTreeNodes(pNode2, pNode1, NULL);

    printf("One path should be found in Test3.\n");
    Test("Test3", pNode5, 15);

    DestroyTree(pNode5);
}

// 1
//  \
//   2
//    \
//     3
//      \
//       4
//        \
//         5
// 没有路径上面的结点和为16
void Test4() {
    BinaryTreeNode* pNode1 = CreateBinaryTreeNode(1);
    BinaryTreeNode* pNode2 = CreateBinaryTreeNode(2);
    BinaryTreeNode* pNode3 = CreateBinaryTreeNode(3);
    BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4);
    BinaryTreeNode* pNode5 = CreateBinaryTreeNode(5);

    ConnectTreeNodes(pNode1, NULL, pNode2);
    ConnectTreeNodes(pNode2, NULL, pNode3);
    ConnectTreeNodes(pNode3, NULL, pNode4);
    ConnectTreeNodes(pNode4, NULL, pNode5);

    printf("No paths should be found in Test4.\n");
    Test("Test4", pNode1, 16);

    DestroyTree(pNode1);
}

// 树中只有1个结点
void Test5() {
    BinaryTreeNode* pNode1 = CreateBinaryTreeNode(1);

    printf("One path should be found in Test5.\n");
    Test("Test5", pNode1, 1);

    DestroyTree(pNode1);
}

// 树中没有结点
void Test6() {
    printf("No paths should be found in Test6.\n");
    Test("Test6", NULL, 0);
}

int main(int argc, char** argv) {
    Test1();
    Test2();
    Test3();
    Test4();
    Test5();
    Test6();

    return 0;
}