剑指Offer面试题：23.二叉树中和为某一值的路径

一、题目：二叉树中和为某一值的路径

题目：输入一棵二叉树和一个整数，打印出二叉树中结点值的和为输入整数的所有路径。从树的根结点开始往下一直到叶结点所经过的结点形成一条路径。例如输入下图中二叉树和整数22，则打印出两条路径，第一条路径包含结点10、12，第二条路径包含结点10、5和7。

private static void TestPortal(string testName, BinaryTreeNode root, int expectedSum)
{
if (!string.IsNullOrEmpty(testName))
{
Console.WriteLine("{0} begins:", testName);
}

FindPath(root, expectedSum);

Console.WriteLine();
}

private static void SetSubTreeNode(BinaryTreeNode root, BinaryTreeNode lChild, BinaryTreeNode rChild)
{
if (root == null)
{
return;
}

root.leftChild = lChild;
root.rightChild = rChild;
}

private static void ClearUpTreeNode(BinaryTreeNode root)
{
if (root != null)
{
BinaryTreeNode left = root.leftChild;
BinaryTreeNode right = root.rightChild;

root = null;

ClearUpTreeNode(left);
ClearUpTreeNode(right);
}
}

View Code
　　（2）功能、特殊输入测试

//            10
//         /      \
//        5        12
//       /\
//      4  7
// 有两条路径上的结点和为22
public static void Test1()
{
BinaryTreeNode node10 = new BinaryTreeNode(10);
BinaryTreeNode node5 = new BinaryTreeNode(5);
BinaryTreeNode node12 = new BinaryTreeNode(12);
BinaryTreeNode node4 = new BinaryTreeNode(4);
BinaryTreeNode node7 = new BinaryTreeNode(7);

SetSubTreeNode(node10, node5, node12);
SetSubTreeNode(node5, node4, node7);

Console.WriteLine("Two paths should be found in Test1.");
TestPortal("Test1", node10, 22);

ClearUpTreeNode(node10);
}

//            10
//         /      \
//        5        12
//       /\
//      4  7
// 没有路径上的结点和为15
public static void Test2()
{
BinaryTreeNode node10 = new BinaryTreeNode(10);
BinaryTreeNode node5 = new BinaryTreeNode(5);
BinaryTreeNode node12 = new BinaryTreeNode(12);
BinaryTreeNode node4 = new BinaryTreeNode(4);
BinaryTreeNode node7 = new BinaryTreeNode(7);

SetSubTreeNode(node10, node5, node12);
SetSubTreeNode(node5, node4, node7);

Console.WriteLine("No paths should be found in Test2.");
TestPortal("Test2", node10, 15);

ClearUpTreeNode(node10);
}

//               5
//              /
//             4
//            /
//           3
//          /
//         2
//        /
//       1
// 有一条路径上面的结点和为15
public static void Test3()
{
BinaryTreeNode node5 = new BinaryTreeNode(5);
BinaryTreeNode node4 = new BinaryTreeNode(4);
BinaryTreeNode node3 = new BinaryTreeNode(3);
BinaryTreeNode node2 = new BinaryTreeNode(2);
BinaryTreeNode node1 = new BinaryTreeNode(1);

node5.leftChild = node4;
node4.leftChild = node3;
node3.leftChild = node2;
node2.leftChild = node1;

Console.WriteLine("One path should be found in Test3.");
TestPortal("Test3", node5, 15);

ClearUpTreeNode(node5);
}

// 1
//  \
//   2
//    \
//     3
//      \
//       4
//        \
//         5
// 没有路径上面的结点和为16
public static void Test4()
{
BinaryTreeNode node1 = new BinaryTreeNode(1);
BinaryTreeNode node2 = new BinaryTreeNode(2);
BinaryTreeNode node3 = new BinaryTreeNode(3);
BinaryTreeNode node4 = new BinaryTreeNode(4);
BinaryTreeNode node5 = new BinaryTreeNode(5);

node1.leftChild = node2;
node2.leftChild = node3;
node3.leftChild = node4;
node4.leftChild = node5;

Console.WriteLine("No paths should be found in Test4.");
TestPortal("Test4", node1, 16);

ClearUpTreeNode(node1);
}

// 树中只有1个结点
public static void Test5()
{
BinaryTreeNode node1 = new BinaryTreeNode(1);

Console.WriteLine("One paths should be found in Test5.");
TestPortal("Test5", node1, 1);

ClearUpTreeNode(node1);
}

// 树中没有结点
public static void Test6()
{
Console.WriteLine("No paths should be found in Test6.");
TestPortal("Test6", null, 0);
}

3.2 测试结果

作者：周旭龙

出处：http://edisonchou.cnblogs.com

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