Question

我正在构建AVL树。当我输入的值小于10时，效果很好。但是当我给出大于10的代码时，代码将崩溃并说出分段错误并给出错误的输出。这是我的学校作业。

输入是这种格式；

D13 D60 D76 D12 A17 D98 A94 D70 D3 A23 A42 D45 A100 D50 A99 A22 A87 A4
A90 D88 A71 A20 D39 D83 A97 A56 D28 A9 D43 A19 D5 A11 A54 A73 D54 A9 A24 A58 D6 D80 A72 A47 A82 A12 A75 D77 D84 D86 A60 D64 D70 D70 A73 A71 A40 D94 D27 A63 D47 A42 A44 A27 A100 A6 D84 A19 D65 A75 A55 A63 A39 D99 A50 D98 A98 D100 D93 A91 A81 D59 D56 D29 D11 D45 D47 D55 D85 D7 D70 A13 A55 A25 D35 D65 A48 D55 A45 D29 A35 A15 IN

输出如下：

4 6 9 12 13 15 17 19 20 22 23 24 25 27 35 39 40 42 44 45 48 50 58
60 63 71 72 73 75 81 82 87 90 91 97 98

    #include <iostream>
    #include <string>
    using namespace std;

    /* First we are going to design structure for Nodes. */

    struct Node {
    Node* l = NULL; //r of the node
    Node* r = NULL; //l of the node
    int h = 0; //Height of the node
    int d = 0; //Data Part of the node
    };


    Node* getNode(int d){
      Node* node = new Node();
      node->d = d;
      node->l = NULL;
      node->r = NULL;
      node->h = 1;
      return (node);
    }

    int getH(Node* n) { //Getting the Height of Tree
    if (n == NULL)
        return 0;
    return n->h;
    }

    int getBlnc(Node* n){

    if (n == NULL)
        return 0;
    else {
        return getH(n->l) - getH(n->r);
    }
      }

    int havMaxValue(int j, int k){

    if (j > k)
        return j;
    return k;
    }

    /* AVL Rotatations */


    Node* rR(Node* temNode) //Right Rotation{

    Node* x = temNode->l;

    x->r = temNode;
    temNode->l = x->r;

    temNode->h = havMaxValue(getH(temNode->l), getH(temNode->r)) + 1;
    x->h = havMaxValue(getH(x->l), getH(x->r)) + 1;

    return x;
      }

    Node* lR(Node* TempNode) //LeftRotate
    {
    Node* tempNode2 = TempNode->r;
    Node* TemNode1 = tempNode2->l;

    tempNode2->l = TempNode;
    TempNode->r = TemNode1;

    TempNode->h = (havMaxValue(getH(TempNode->l), getH(TempNode->r)) + 1);
    tempNode2->h = (havMaxValue(getH(tempNode2->l), getH(tempNode2->r)) + 1);
    return tempNode2;
    }

    Node* inNode(Node* tempNode, int value) //Insert New Node
    {

    if (tempNode == NULL)
        return (getNode(value));

    if (value < tempNode->d)
        tempNode->l = inNode(tempNode->l, value);
    else if (value > tempNode->d)
        tempNode->r = inNode(tempNode->r, value);
    else
        return tempNode;

    tempNode->h = 1 + havMaxValue(getH(tempNode->l), getH(tempNode->r));

    int blnc = getBlnc(tempNode); //Balance Variable

    if (blnc > 1 && value < tempNode->l->d)
        return rR(tempNode);

    if (blnc < -1 && value > tempNode->r->d)
        return lR(tempNode);

    if (blnc > 1 && value > tempNode->l->d) {
        tempNode->l = lR(tempNode->l);
        return rR(tempNode);
    }

    if (blnc < -1 && value < tempNode->r->d) {
        tempNode->r = rR(tempNode->r);
        return lR(tempNode);
    }

    return tempNode;
    }

    /* Deletion */

    Node* nodeHavingMinVal(Node* temp) //Mininum Value Node
    {
    Node* tempNode = temp;
    while (tempNode->l != NULL)
        tempNode = tempNode->l;

    return tempNode;
    }

    Node* extractNode(Node* tempNode, int key) //DeleteNode
    {

    if (tempNode == NULL)
        return tempNode;

    if (key < tempNode->d)
        tempNode->l = extractNode(tempNode->l, key);

    else if (key > tempNode->d)
        tempNode->r = extractNode(tempNode->r, key);

    else {
        if ((tempNode->l == NULL) || (tempNode->r == NULL)) {
            Node* TempNode = tempNode->l ? tempNode->l : tempNode->r;

            if (TempNode == NULL) {
                TempNode = tempNode;
                tempNode = NULL;
            }
            else
                *tempNode = *TempNode;
        }
        else {
            Node* TempNode = nodeHavingMinVal(tempNode->r);
            tempNode->d = TempNode->d;
            tempNode->r = extractNode(tempNode->r, TempNode->d);
        }
    }

    if (tempNode == NULL)
        return tempNode;

    tempNode->h = 1 + max(getH(tempNode->l), getH(tempNode->r));

    int blnc = getBlnc(tempNode);

    if (blnc > 1 && getBlnc(tempNode->l) >= 0)
        return rR(tempNode);

    if (blnc > 1 && getBlnc(tempNode->l) < 0) {
        tempNode->l = lR(tempNode->l);
        return rR(tempNode);
    }

    if (blnc < -1 && getBlnc(tempNode->r) <= 0)
        return lR(tempNode);

    if (blnc < -1 && getBlnc(tempNode->r) > 0) {
        tempNode->r = rR(tempNode->r);
        return lR(tempNode);
    }

    return tempNode;
    }

    /* Graph Traversal */

    void POST(Node* node)
    {
    if (node == NULL)
        return;

    POST(node->l);
    POST(node->r);

    cout << node->d << " ";
    }

    void IN(Node* node)
    {
    if (node == NULL)
        return;

    IN(node->l);
    cout << node->d << " ";
    IN(node->r);
    }

    void PRE(Node* node)
    {
    if (node == NULL)
        return;

    cout << node->d << " ";

    PRE(node->l);
    PRE(node->r);
    }

    int main()
    {
    Node* root = NULL;
    char ch[5];
    int num;
    int i = 1;

    top:
       for (; i > 0;) {

        cin >> ch[0];

        if (ch[0] == 'A') {
            int num;
            cin >> num;
            root = inNode(root, num);
            goto top;
        }

        if (ch[0] == 'D') {
            int num;
            cin >> num;
            root = extractNode(root, num); //Delete Node
            if (root == NULL) {
                cout << "EMPTY";
                break;
            }
            goto top;
        }

        cin >> ch[1];
        if (ch[0] == 'I' and ch[1] == 'N') {
            IN(root);
            break;
        }

          cin >> ch[2];
          if (ch[0] == 'P' and ch[1] == 'R' and ch[2] == 'E') {
            PRE(root);
            break;
        }

        cin >> ch[3];
        if (ch[0] == 'P' and ch[1] == 'O' and ch[2] == 'S' and ch[3] == 'T') 
        {
            POST(root);
            break;
        }
    }

    return 0;
    }

Answer 1

您的树变为无效，导致extractNode无限调用自身，并导致堆栈溢出。检查问题出在哪里的最简单方法是编写一个遍历整个树的函数，并在每次修改后调用它（带有日志记录）。段错误之前的最后一个修改是问题。

您可以通过修改代码来确认这一点：

Node* extractNode(Node* tempNode, int key, int depth) //DeleteNode
{
if (depth > 10)
    printf("depth=%d\n", depth);

if (tempNode == NULL)
    return tempNode;

if (key < tempNode->d)
    tempNode->l = extractNode(tempNode->l, key, depth + 1);

else if (key > tempNode->d)
    tempNode->r = extractNode(tempNode->r, key, depth + 1);

else {
    if ((tempNode->l == NULL) || (tempNode->r == NULL)) {
        Node* TempNode = tempNode->l ? tempNode->l : tempNode->r

以此类推。最初以零深度调用它。您会看到深度迅速增加，然后堆栈溢出。

depth = 11
  深度= 12
  深度= 13
     << 很多行 >>
  深度= 104724
  深度= 104725
  深度= 104726
  深度= 104727
  深度= 104728
  深度= 104729
  深度= 104730
  深度= 104731
  深度= 104732
  深度= 104733
  深度= 104734
  分割错误

为什么代码在输入大于10时给出分段错误？

1 个答案: