chore(C): add breadth-first search and depth-first search (#644)

Co-authored-by: Rahul Rajeev Pillai <66192267+Ashborn-SM@users.noreply.github.com>

algorithms/C/README.md

@@ -16,6 +16,8 @@
 ## Graphs
 
 - [Prim's Algorithm](graphs/Prim's-algorithm.c)
+- [Breadth First Search](graphs/breadth-first-search.c)
+- [Depth First Search](graphs/depth-first-search.c)
 
 ## Linked Lists
 

algorithms/C/graphs/breadth-first-search.c

@@ -0,0 +1,105 @@
+/* Breadth-first search (BFS) is an algorithm for searching a tree data structure for a node that 
+satisfies a given property. It starts at the tree root and explores all nodes at the present depth prior 
+to moving on to the nodes at the next depth level.*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+// Adjacency Matrix
+int G[][5] = {
+    {0, 1, 1, 1, 0},
+    {1, 0, 1, 0, 0},
+    {1, 1, 0, 0, 1},
+    {1, 0, 0, 0, 0},
+    {0, 0, 1, 0, 0}};
+
+int start = 0, n = 5;
+
+// Node Structure
+struct Node
+{
+    int data;
+    struct Node *next;
+};
+
+struct Node *front = NULL;
+struct Node *rear = NULL;
+
+void enqueue(int x)
+{
+    struct Node *temp = malloc(sizeof(*temp));
+    temp->data = x;
+    temp->next = NULL;
+
+    if (front == NULL)
+    {
+        front = temp;
+        rear = temp;
+    }
+    else
+    {
+        rear->next = temp;
+        rear = temp;
+    }
+}
+
+int dequeue()
+{
+    int x = -1;
+    if (front == NULL)
+    {
+        printf("Queue is empty\n");
+    }
+    else
+    {
+        struct Node *temp = front;
+        x = temp->data;
+        front = front->next;
+        free(temp);
+    }
+    return x;
+}
+
+int isEmpty()
+{
+    if (front == NULL)
+    {
+        return 1;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+void BFSTraversal(int G[][5], int start, int n)
+{
+    int i, j;
+    int visited[5] = {0};
+    enqueue(start);
+    visited[start] = 1;
+    while (!isEmpty())
+    {
+        i = dequeue();
+        printf("%d ", i);
+        for (j = 1; j < n; j++)
+        {
+            if (G[i][j] == 1 && visited[j] == 0)
+            {
+                enqueue(j);
+                visited[j] = 1;
+            }
+        }
+    }
+}
+
+int main()
+{
+    BFSTraversal(G, start, n);
+    return 0;
+}
+
+/*
+Output:
+0 1 2 3 4
+*/

algorithms/C/graphs/depth-first-search.c

@@ -0,0 +1,43 @@
+/* Depth-first search (DFS) is an algorithm for traversing or searching tree or graph data structures. 
+The algorithm starts at the root node (selecting some arbitrary node as the root node in the case of a graph) and 
+explores as far as possible along each branch before backtracking.*/
+
+#include <stdio.h>
+
+// Adjacency Matrix
+int G[][5] = {
+    {0, 1, 1, 1, 0},
+    {1, 0, 1, 0, 0},
+    {1, 1, 0, 0, 1},
+    {1, 0, 0, 0, 0},
+    {0, 0, 1, 0, 0}};
+
+int start = 0, n = 5;
+
+void DFSTraversal(int G[][5], int start, int n)
+{
+    static int visited[5] = {0};
+    int j;
+    if (visited[start] == 0)
+    {
+        printf("%d ", start);
+        visited[start] = 1;
+        for (j = 1; j < n; j++)
+        {
+            if (G[start][j] == 1 && visited[j] == 0){
+                DFSTraversal(G, j, n);
+            }
+        }
+    }
+}
+
+int main()
+{
+    DFSTraversal(G, start, n);
+    return 0;
+}
+
+/*
+Output:
+0 1 2 4 3 
+*/