Cでの深さ優先走査

Cプログラミング言語でのDepth First Traversal（またはDepth First Search）の実装は表示されません。参考のために、例に従ってグラフモデルとしてこれを取り上げます-

Cでの実装

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

#define MAX 5

struct Vertex {
   char label;
   bool visited;
};

//stack variables

int stack[MAX];
int top = -1;

//graph variables

//array of vertices
struct Vertex* lstVertices[MAX];

//adjacency matrix
int adjMatrix[MAX][MAX];

//vertex count
int vertexCount = 0;

//stack functions

void push(int item) {
   stack[&plus;&plus;top] = item;
}

int pop() {
   return stack[top--];
}

int peek() {
   return stack[top];
}

bool isStackEmpty() {
   return top == -1;
}

//graph functions

//add vertex to the vertex list
void addVertex(char label) {
   struct Vertex* vertex = (struct Vertex*) malloc(sizeof(struct Vertex));
   vertex->label = label;
   vertex->visited = false;
   lstVertices[vertexCount&plus;&plus;] = vertex;
}

//add edge to edge array
void addEdge(int start,int end) {
   adjMatrix[start][end] = 1;
   adjMatrix[end][start] = 1;
}

//display the vertex
void displayVertex(int vertexIndex) {
   printf("%c ",lstVertices[vertexIndex]->label);
}

//get the adjacent unvisited vertex
int getAdjUnvisitedVertex(int vertexIndex) {
   int i;

   for(i = 0; i < vertexCount; i&plus;&plus;) {
      if(adjMatrix[vertexIndex][i] == 1 && lstVertices[i]->visited == false) {
         return i;
      }
   }

   return -1;
}

void depthFirstSearch() {
   int i;

  //mark first node as visited
   lstVertices[0]->visited = true;

  //display the vertex
   displayVertex(0);

  //push vertex index in stack
   push(0);

   while(!isStackEmpty()) {
     //get the unvisited vertex of vertex which is at top of the stack
      int unvisitedVertex = getAdjUnvisitedVertex(peek());

     //no adjacent vertex found
      if(unvisitedVertex == -1) {
         pop();
      } else {
         lstVertices[unvisitedVertex]->visited = true;
         displayVertex(unvisitedVertex);
         push(unvisitedVertex);
      }
   }

  //stack is empty, search is complete, reset the visited flag
   for(i = 0;i < vertexCount;i&plus;&plus;) {
      lstVertices[i]->visited = false;
   }
}

int main() {
   int i, j;

   for(i = 0; i < MAX; i&plus;&plus;)   //set adjacency {
      for(j = 0; j < MAX; j&plus;&plus;)//matrix to 0
         adjMatrix[i][j] = 0;
   }

   addVertex('S');  //0
   addVertex('A');  //1
   addVertex('B');  //2
   addVertex('C');  //3
   addVertex('D');  //4

   addEdge(0, 1);   //S - A
   addEdge(0, 2);   //S - B
   addEdge(0, 3);   //S - C
   addEdge(1, 4);   //A - D
   addEdge(2, 4);   //B - D
   addEdge(3, 4);   //C - D

   printf("Depth First Search: ")
   depthFirstSearch();

   return 0;
}

上記のプログラムをコンパイルして実行すると、次の結果が生成されます-

出力

Depth First Search: S A D B C

Data-structures-algorithms-depth-first-traversal-in-c

Cでの深さ優先走査

Cでの実装

出力