標頭檔案 UnionFind3.h

#ifndef UNIONFIND3_H_INCLUDED
#define UNIONFIND3_H_INCLUDED
#include "stdlib.h"
#include "ASSERT.h"
typedef struct{
    int* parent;
    int* rank;//rank[i]表示以i為根的集合中樹的層數
    int count;
}Union;

void unionFind3Init(Union *un,int n);
void freeUnion3(Union *un);
int unionFind3(Union *un,int p);
int isConnected3(Union *un,int p,int q);
void unionElements3(Union *un,int p,int q);
#endif // UNIONFIND_H_INCLUDED
 

c程式碼 UnionFind3.c

#include "UnionFind3.h"
/*********************************************
*函式名：並查集的初始化
*********************************************/
void unionFind3Init(Union *un,int n){
    int i;
    un->count = n;
    un->parent = (int*)malloc(n*sizeof(int));
    un->rank = (int*)malloc(n*sizeof(int));
    for(i=0;i<n;i++){
        un->parent[i] = i;
        un->rank[i] = 1;
    }
}
/*********************************************
*函式名：並查集將空間釋放
*********************************************/
void freeUnion3(Union *un){
    free(un->parent);
    free(un->rank);
}

/*********************************************
*函式名：返回並查集中p的ID(採用路徑壓縮)
*********************************************/
int unionFind3(Union *un,int p){
    assert(p >= 0 && p< un->count);
//    while(p != un->parent[p]){
//        un->parent[p] = un->parent[un->parent[p]];  //路徑壓縮
//        p = un->parent[p];
//    }
//    return p;

    if(p != un->parent[p]){                           //使用遞迴的方法進行路徑壓縮
        un->parent[p] = unionFind3(un,un->parent[p]);
    }
    return un->parent[p];
}
/*********************************************
*函式名：判斷並查集中p和q是否是一個集合
*********************************************/
int isConnected3(Union *un,int p,int q){
    return unionFind3(un,p) == unionFind3(un,q) ;
}
/*********************************************
*函式名：並查集的合併
*********************************************/
void unionElements3(Union *un,int p,int q){
    int pRoot = unionFind3(un,p);
    int qRoot = unionFind3(un,q);

    if(pRoot == qRoot){
        return ;
    }
    else if(un->rank[pRoot] < un->rank[qRoot]){
        un->parent[pRoot] = qRoot;
    }
    else if(un->rank[pRoot] > un->rank[qRoot]){
        un->parent[qRoot] = pRoot;
    }
    else{
        un->parent[pRoot] = qRoot;
        un->rank[qRoot] += 1;
    }
}