다음은 C언어로 작성한 프림(Prim) 알고리즘 소스 코드입니다. 프림 알고리즘은 그래프에서 최소신장트리를 만드는 대표적인 탐욕(Greedy) 알고리즘입니다.
//Array.h
#pragma once
typedef void * Element;
typedef struct _Array Array;
struct _Array
{
Element *base;
int capacity;
int usage;
};
typedef Element *Iterator;
Array *New_Array();
void Delete_Array(Array *arr);
void Array_SetSize(Array *arr,int capacity,Element data);
void Array_PushBack(Array *arr,Element data);
void Array_Insert(Array *arr,Iterator pos,Element data);
void Array_SetAt(Array *arr,int index,Element data);
Element Array_GetAt(Array *arr,int index);
Iterator Array_Begin(Array *arr);
Iterator Array_End(Array *arr);
void Array_Erase(Array *arr,Iterator pos);
//Array.c
#include "Array.h"
#include <malloc.h>
#include <memory.h>
Array *New_Array()
{
Array *arr = 0;
arr = (Array *)malloc(sizeof(Array));
arr->base = 0;
arr->capacity = arr->usage = 0;
return arr;
}
void Delete_Array(Array *arr)
{
if(arr->base)
{
free(arr->base);
}
free(arr);
}
void Array_SetSize(Array *arr,int capacity,Element data)
{
arr->capacity = capacity;
arr->base = (Element *)realloc(arr->base,sizeof(Element)*arr->capacity);
for( ;arr->usage<arr->capacity; arr->usage++)
{
arr->base[arr->usage] = data;
}
}
void Array_PushBack(Array *arr,Element data)
{
Iterator at = Array_End(arr);
Array_Insert(arr,at,data);
}
void Array_Insert(Array *arr,Iterator pos,Element data)
{
int index = pos - arr->base;
int mcount = arr->usage - index;
if(arr->capacity == arr->usage)
{
if(arr->capacity)
{
arr->capacity*=2;
}
else
{
arr->capacity = 1;
}
arr->base = (Element *)realloc(arr->base,sizeof(Element)*arr->capacity);
}
memcpy(arr->base+index+1,arr->base+index,sizeof(Element)*mcount);
arr->base[index] = data;
arr->usage++;
}
void Array_SetAt(Array *arr,int index,Element data)
{
if((index>=0)&&(index<arr->usage))
{
arr->base[index] = data;
}
}
Element Array_GetAt(Array *arr,int index)
{
if((index>=0)&&(index<arr->usage))
{
return arr->base[index];
}
return 0;
}
Iterator Array_Begin(Array *arr)
{
return arr->base;
}
Iterator Array_End(Array *arr)
{
return arr->base+arr->usage;
}
void Array_Erase(Array *arr,Iterator pos)
{
int index = pos - arr->base;
int mcount = arr->usage - index -1;
memcpy(pos,pos+1,sizeof(Element)*mcount);
arr->usage--;
}
//Graph.h
#pragma once
#include "Array.h"
typedef const char * Vertex;
typedef struct _Edge Edge;
struct _Edge
{
Vertex ep1;
Vertex ep2;
int weight;
};
typedef struct _Graph Graph;
struct _Graph
{
Array *vertexs;
Array *edges;
};
Graph *New_Graph();
void Delete_Graph(Graph *graph);
int Graph_AddVertex(Graph *graph,Vertex pt);
int Graph_AddEdge(Graph *graph,Vertex ep1, Vertex ep2, int weight);
int Graph_ExistVertex(Graph *graph,Vertex pt);
int Graph_ExistEdge(Graph *graph,Vertex ep1, Vertex ep2);
void Graph_View(Graph *graph);
void Graph_ViewVertexs(Graph *graph);
void Graph_ViewEdges(Graph *graph);
void Graph_FindNeighvor(Graph *graph,Vertex ep, Array *neighvor);
int Graph_GetWeight(Graph *graph,Vertex ep1, Vertex ep2);
int Graph_GetVtCnt(Graph *graph);
Vertex Graph_GetFront(Graph *graph);
int Edge_Include(Edge *edge,Vertex pt);
//Graph.c
#include "Graph.h"
#include <malloc.h>
#include <string.h>
#include <stdio.h>
Edge *New_Edge(Vertex ep1, Vertex ep2, int weight)
{
Edge *edge = 0;
edge = (Edge *)malloc(sizeof(Edge));
edge->ep1 = ep1;
edge->ep2 = ep2;
edge->weight = weight;
return edge;
}
Vertex Edge_AnOther(Edge *edge,Vertex pt)
{
if(strcmp(edge->ep1,pt)==0)
{
return edge->ep2;
}
if(strcmp(edge->ep2,pt)==0)
{
return edge->ep1;
}
return "";
}
int Edge_Include(Edge *edge,Vertex pt)
{
return (strcmp(edge->ep1,pt)==0)||(strcmp(edge->ep2,pt)==0);
}
Graph *New_Graph()
{
Graph *graph = 0;
graph = (Graph *)malloc(sizeof(Graph));
graph->vertexs = New_Array();
graph->edges = New_Array();
return graph;
}
void Delete_Graph(Graph *graph)
{
Iterator seek = 0, end = 0;
Edge *edge = 0;
seek = Array_Begin(graph->edges);
end = Array_End(graph->edges);
for(seek = seek; seek != end; ++seek)
{
edge = (Edge *)(*seek);
free(edge);
}
Delete_Array(graph->vertexs);
Delete_Array(graph->edges);
free(graph);
}
int Graph_AddVertex(Graph *graph,Vertex pt)
{
if(Graph_ExistVertex(graph,pt))
{
return 0;
}
Array_PushBack(graph->vertexs,(Element)pt);
return 1;
}
int Graph_AddEdge(Graph *graph,Vertex ep1, Vertex ep2, int weight)
{
if(Graph_ExistVertex(graph,ep1) && Graph_ExistVertex(graph,ep2))
{
Edge *edge = 0;
if(Graph_ExistEdge(graph,ep1,ep2))
{
return 0;
}
edge = New_Edge(ep1,ep2,weight);
Array_PushBack(graph->edges,edge);
return 1;
}
return 0;
}
int Graph_ExistVertex(Graph *graph,Vertex pt)
{
Iterator seek = 0, end = 0;
Vertex stored_pt = 0;
seek = Array_Begin(graph->vertexs);
end = Array_End(graph->vertexs);
for(seek = seek; seek != end; ++seek)
{
stored_pt = (Vertex)(*seek);
if(strcmp(stored_pt,pt)==0)
{
return 1;
}
}
return 0;
}
int Graph_ExistEdge(Graph *graph,Vertex ep1, Vertex ep2)
{
Iterator seek = 0, end = 0;
Edge *stored_eg = 0;
seek = Array_Begin(graph->edges);
end = Array_End(graph->edges);
for(seek = seek; seek != end; ++seek)
{
stored_eg = (Edge *)(*seek);
if(Edge_Include(stored_eg,ep1)&&Edge_Include(stored_eg,ep2))
{
return 1;
}
}
return 0;
}
void Graph_View(Graph *graph)
{
Graph_ViewVertexs(graph);
Graph_ViewEdges(graph);
}
void Graph_ViewVertexs(Graph *graph)
{
Iterator seek = 0, end = 0;
Vertex pt = 0;
printf("정점 개수:%d\n",graph->vertexs->usage);
seek = Array_Begin(graph->vertexs);
end = Array_End(graph->vertexs);
for(seek = seek; seek != end; ++seek)
{
pt = (Vertex)(*seek);
printf("%s\n",pt);
}
}
void Graph_ViewEdges(Graph *graph)
{
Iterator seek = 0, end = 0;
Edge *edge = 0;
printf("간선 개수:%d\n",graph->edges->usage);
seek = Array_Begin(graph->edges);
end = Array_End(graph->edges);
for(seek = seek; seek != end; ++seek)
{
edge = (Edge *)(*seek);
printf("(%s ,%s):%d\n",edge->ep1,edge->ep2,edge->weight);
}
}
void Graph_FindNeighvor(Graph *graph,Vertex ep, Array *neighvor)
{
Iterator seek = 0, end = 0;
Edge *edge = 0;
seek = Array_Begin(graph->edges);
end = Array_End(graph->edges);
for(seek = seek; seek != end; ++seek)
{
edge = (Edge *)(*seek);
if(Edge_Include(edge,ep))
{
Vertex opt;
opt = Edge_AnOther(edge,ep);
Array_PushBack(neighvor,(Element)opt);
}
}
}
int Graph_GetWeight(Graph *graph,Vertex ep1, Vertex ep2)
{
Iterator seek = 0, end = 0;
Edge *edge = 0;
seek = Array_Begin(graph->edges);
end = Array_End(graph->edges);
for(seek = seek; seek != end; ++seek)
{
edge = (Edge *)(*seek);
if(Edge_Include(edge,ep1)&&Edge_Include(edge,ep2))
{
return edge->weight;
}
}
return -1;
}
int Graph_GetVtCnt(Graph *graph)
{
return graph->vertexs->usage;
}
Vertex Graph_GetFront(Graph *graph)
{
Iterator front = Array_Begin(graph->vertexs);
return (Vertex)front[0];
}
//Prim.h #pragma once #include "Graph.h" Graph *Prim(Graph *origin);
//Prim.c
#include "Prim.h"
Graph *Prim(Graph *origin);
void SelectVertex(Graph *mstree,Graph *origin);
Graph *Prim(Graph *origin)
{
Graph *mstree = 0;
Vertex vt;
mstree = New_Graph();
vt = Graph_GetFront(origin);
Graph_AddVertex(mstree,vt);
while(Graph_GetVtCnt(mstree)<Graph_GetVtCnt(origin))
{
SelectVertex(mstree,origin);
}
return mstree;
}
int IsOnlyOneInclude(Edge *edge, Array *selected);
void SelectVertex(Graph *mstree,Graph *origin)
{
Array *selected = mstree->vertexs;
Array *ori_edges = origin->edges;
Edge *selectedge=0;
Iterator seek = 0, end = 0;
Edge *edge = 0;
seek = Array_Begin(ori_edges);
end = Array_End(ori_edges);
for(seek = seek; seek != end; ++seek)
{
edge = (Edge *)(*seek);
if(IsOnlyOneInclude(edge,selected))
{
if(selectedge)
{
if(selectedge->weight>edge->weight)
{
selectedge = edge;
}
}
else
{
selectedge = edge;
}
}
}
Graph_AddVertex(mstree,selectedge->ep1);
Graph_AddVertex(mstree,selectedge->ep2);
Graph_AddEdge(mstree,selectedge->ep1,selectedge->ep2,selectedge->weight);
}
int IsOnlyOneInclude(Edge *edge, Array *selected)
{
Iterator seek = 0, end = 0;
int cnt = 0;
Vertex vt;
seek = Array_Begin(selected);
end = Array_End(selected);
for(seek = seek; seek != end; ++seek)
{
vt = (Vertex)(*seek);
if(Edge_Include(edge,vt))
{
cnt++;
}
}
return cnt==1;
}
//Program.c
#include "Prim.h"
Graph * InitSimulation();
int main()
{
Graph *origin = 0;
Graph *mstree = 0;
origin = InitSimulation();
mstree = Prim(origin);
Graph_View(mstree);
Delete_Graph(origin);
Delete_Graph(mstree);
return 0;
}
Graph * InitSimulation()
{
Graph *graph = New_Graph();
Graph_AddVertex(graph,"A");
Graph_AddVertex(graph,"B");
Graph_AddVertex(graph,"C");
Graph_AddVertex(graph,"D");
Graph_AddVertex(graph,"E");
Graph_AddVertex(graph,"F");
Graph_AddVertex(graph,"G");
Graph_AddVertex(graph,"H");
Graph_AddEdge(graph,"A","B",5);
Graph_AddEdge(graph,"A","D",3);
Graph_AddEdge(graph,"A","E",4);
Graph_AddEdge(graph,"B","D",3);
Graph_AddEdge(graph,"B","H",2);
Graph_AddEdge(graph,"C","D",3);
Graph_AddEdge(graph,"C","G",4);
Graph_AddEdge(graph,"D","H",5);
Graph_AddEdge(graph,"D","E",3);
Graph_AddEdge(graph,"D","F",3);
Graph_AddEdge(graph,"E","F",2);
Graph_AddEdge(graph,"F","G",6);
Graph_AddEdge(graph,"G","H",3);
Graph_View(graph);
return graph;
}
▷ 실행 결과
정점 개수:8 A B C D E F G H 간선 개수:13 (A ,B):5 (A ,D):3 (A ,E):4 (B ,D):3 (B ,H):2 (C ,D):3 (C ,G):4 (D ,H):5 (D ,E):3 (D ,F):3 (E ,F):2 (F ,G):6 (G ,H):3 정점 개수:8 A D B H C E F G 간선 개수:7 (A ,D):3 (B ,D):3 (B ,H):2 (C ,D):3 (D ,E):3 (E ,F):2 (G ,H):3