双亲树-等价类

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用双亲树的思想实现了一个等价类。完成了路径压缩。算法仍然采用严蔚敏的教材中等价类章节中的算法。
/*  Author : Moyiii *  Mail:  lc09@vip.qq.com *  树的双亲表示法&等价类实现 *  仅作学习之用，当然如果 *  你想拿去用，随你好啦。*/#include<iostream>using namespace std;#define MAX_NODES 100class PTree{public:    PTree();    void print();    void input();    int findClass(int a);private:    void mergeNodes(int a,int b);    void fixNode(int a);    int nodes[MAX_NODES];    int nodeNum;};PTree :: PTree(){    nodeNum = 0;}//输入两个数字，然后将这两个数字所在的集合合并成一个集合void PTree :: input(){    cout << "Please enter the amount of the nodes:";    cin >> nodeNum;    for(int i = 0; i < nodeNum; ++i)    {        nodes[i] = -1;    }    cout << "Please enter two numbers that belong to the same class" << endl;    cout << "End with -1 -1" << endl;    int m,n;    while(cin >> m >> n && m != -1 && n != -1)    {        if(m > nodeNum || n > nodeNum)        {            cout << "Error data!" << endl;            continue;        }        //从根合并        int i = findClass(m);        int j = findClass(n);        mergeNodes(i,j);    }}//找到根int PTree :: findClass(int a){    fixNode(a);    while(nodes[a-1] > 0)    {        a = nodes[a - 1];    }    return a;}//将从a到a的根部之间的节点都直接指向a的根用来压缩路径void PTree :: fixNode(int a){    //找到a的根节点    int paren = a;    while(nodes[paren - 1] > 0)    {        paren = nodes[paren - 1];    }    int temp = a;    //将a到根之间的节点都指向paren    while(nodes[temp - 1] > 0)    {        int x = nodes[temp - 1];        nodes[temp - 1] = paren;        temp = x;    }    return;}//合并两个等价类的根部，把节点少的合并到节点多的地方void PTree :: mergeNodes(int a, int b){    //根节点的数据是负数，其绝对值代表这个等价类中有多少个数据    if(a == b)    {        return;    }        if(nodes[a - 1] < nodes[b - 1])    {        nodes[a - 1] += nodes[b - 1];        nodes[b - 1] = a;        fixNode(a);    }    else    {        nodes[b - 1] += nodes[a - 1];        nodes[a - 1] = b;        fixNode(b);    }}//打印函数void PTree :: print(){   cout << "----------Datas-----------" << endl;   for(int i = 0; i < nodeNum; ++i)   {       cout << i+1 << " " << nodes[i] << endl;   }   return;}/*测试数据83 56 73 7-1 -1*/int main(){    PTree eq;    eq.input();    cout << eq.findClass(3) << endl;    eq.print();    return 0;}
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