WAP for Depth First Binary Tree Search using Recursion

Levels of difficulty: / perform operation:

The following C program, using recursion, performs a Depth First Search traversal. Depth-first search (DFS) is an algorithm for traversing or searching a tree, tree structure or graph. The concept of backtracking is used in DFS. In this program we are performing DFS on a binary tree. In DFS, the deepest and univisited node is visited and backtracks to it’s parent node if no siblings of that node exists.
Conditions: The DFS works on acyclic graph. DFS may fail if it enters a cycle. Care must be taken by not extending a path to a node if it already has.

Here is the source code of the C program to apply DFS on a binary tree recursively. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

```#include <stdio.h>
#include <stdlib.h>
struct node {
int a;
struct node *left;
struct node *right;
}
;
void generate(struct node **, int);
void DFS(struct node *);
void delete(struct node **);
int main() {
int choice = 0, num, flag = 0, key;
do {
printf("\nEnter your choice:\n1. Insert\n2. Perform DFS Traversal\n3. Exit\nChoice: ");
scanf("%d", &choice);
switch(choice) {
case 1:
printf("Enter element to insert: ");
scanf("%d", &num);
break;
case 2:
break;
case 3:
printf("Memory Cleared\nPROGRAM TERMINATED\n");
break;
default:
printf("Not a valid input, try again\n");
}
}
while (choice != 3);
return 0;
}
void generate(struct node **head, int num) {
*head = (struct node *)malloc(sizeof(struct node));
} else {
while (temp != NULL) {
if (num > temp->a) {
prev = temp;
temp = temp->right;
} else {
prev = temp;
temp = temp->left;
}
}
temp = (struct node *)malloc(sizeof(struct node));
temp->a = num;
if (num >= prev->a) {
prev->right = temp;
} else {
prev->left = temp;
}
}
}
}
}
}
}
}
}
}
}```

Output

```Enter your choice:
1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 1
Enter element to insert: 5

1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 1
Enter element to insert: 3

1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 1
Enter element to insert: 4

1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 1
Enter element to insert: 2

1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 1
Enter element to insert: 7

1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 1
Enter element to insert: 8

1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 1
Enter element to insert: 6

1. Insert
2. Perform DFS Traversal
3. Exit
Choice: 2
2  4  3  6  8  7  5
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