deep first search (#87)

* undirected graph

* deep first search

* fixed LGTM

Author: realDuYuanChao

datastructures/graph/deep_first_search_of_graph.c

@@ -0,0 +1,56 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdbool.h>
+
+#define VERTEX_NUM 5
+typedef char ElemType;
+typedef struct {
+    ElemType vertex[VERTEX_NUM];
+    int edge[VERTEX_NUM][VERTEX_NUM];
+} Graph;
+
+bool visited[VERTEX_NUM];
+ElemType dfsPath[VERTEX_NUM];
+int count = 0;
+void deepFirstSearch(Graph *g, int start) {
+    dfsPath[count++] = g->vertex[start];
+    visited[start] = true;
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        if (g->edge[start][i] == 1 && !visited[i]) {
+            deepFirstSearch(g, i);
+        }
+    }
+}
+
+void test() {
+    Graph graph;
+    /* init vertexes */
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        graph.vertex[i] = 'A' + i;
+    }
+
+    /* init edges: see images/adjacency_matrix.png */
+    int matrix[VERTEX_NUM][VERTEX_NUM] = {
+            {0, 1, 0, 1, 0},
+            {1, 0, 1, 1, 0},
+            {0, 1, 0, 0, 1},
+            {1, 1, 0, 0, 1},
+            {0, 0, 1, 1, 0}
+    };
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        for (int j = 0; j < VERTEX_NUM; ++j) {
+            graph.edge[i][j] = matrix[i][j];
+        }
+    }
+
+    ElemType path[] = {'A', 'B', 'C', 'E', 'D'};
+    deepFirstSearch(&graph, 0);
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        assert(path[i] == dfsPath[i]);
+    }
+}
+
+int main() {
+    test();
+    return 0;
+}

datastructures/graph/undirected_graph.c

@@ -0,0 +1,76 @@
+#include <assert.h>
+#include <stdio.h>
+
+#define VERTEX_NUM 5
+typedef char ElemType;
+typedef struct {
+    ElemType vertex[VERTEX_NUM];
+    int edge[VERTEX_NUM][VERTEX_NUM];
+} Graph;
+
+void initGraph(Graph *graph) {
+    /* init vertex */
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        graph->vertex[i] = '\0';
+    }
+
+    /* init edge */
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        for (int j = 0; j < VERTEX_NUM; ++j) {
+            graph->edge[i][j] = 0;
+        }
+    }
+}
+
+int getDegree(Graph *graph, ElemType vertex) {
+    int vertexIndex = -1;
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        if (vertex == graph->vertex[i]) {
+            vertexIndex = i;
+            break;
+        }
+    }
+    if (vertexIndex == -1) {
+        perror("vertex not found.");
+    }
+    int sum = 0;
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        sum = sum + graph->edge[vertexIndex][i];
+    }
+    return sum;
+}
+
+void test() {
+    Graph graph;
+    initGraph(&graph);
+
+    /* init vertexes */
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        graph.vertex[i] = 'A' + i;
+    }
+
+    /* init edges: see images/adjacency_matrix.png */
+    int matrix[VERTEX_NUM][VERTEX_NUM] = {
+            {0, 1, 0, 1, 0},
+            {1, 0, 1, 1, 0},
+            {0, 1, 0, 0, 1},
+            {1, 1, 0, 0, 1},
+            {0, 0, 1, 1, 0}
+    };
+    for (int i = 0; i < VERTEX_NUM; ++i) {
+        for (int j = 0; j < VERTEX_NUM; ++j) {
+            graph.edge[i][j] = matrix[i][j];
+        }
+    }
+
+    assert(2 == getDegree(&graph, 'A'));
+    assert(3 == getDegree(&graph, 'B'));
+    assert(2 == getDegree(&graph, 'C'));
+    assert(3 == getDegree(&graph, 'D'));
+    assert(2 == getDegree(&graph, 'E'));
+}
+
+int main() {
+    test();
+    return 0;
+}