Here is source code of the C Program to implement depth first search traversal using post order. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

/*
* C Program to Implement Depth First Search Traversal using Post Order
50
/ \
20 30
/ \
70 80
/ \ \
10 40 60
(50, 20, 30, 70, 80, 10, 40, 60)
*/

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


struct btnode {
int value;
struct btnode *l;
struct btnode *r;
};

typedef struct btnode bt;
bt *root;
bt *new, *list;
bt *create_node();
void display(bt *);
void construct_tree();
void dfs(bt *);

void main()
{
construct_tree();
display(root);
printf("\n");
printf("Depth first traversal\n ");
dfs(root);
}

/* Creates an empty node */
bt * create_node()
{
new=(bt *)malloc(sizeof(bt));
new->l = NULL;
new->r = NULL;
}

/* Constructs a tree */
void construct_tree()
{
root = create_node();
root->value = 50;
root->l = create_node();
root->l->value = 20;
root->r = create_node();
root->r->value = 30;
root->l->l = create_node();
root->l->l->value = 70;
root->l->r = create_node();
root->l->r->value = 80;
root->l->r->r = create_node();
root->l->r->r->value = 60;
root->l->l->l = create_node();
root->l->l->l->value = 10;
root->l->l->r = create_node();
root->l->l->r->value = 40;
}

/* Display the elements in a tree using inorder */
void display(bt * list)
{
if (list == NULL)
{
return;
}
display(list->l);
printf("->%d", list->value);
display(list->r);
}

/* Dfs traversal using post order */
void dfs(bt * list)
{
if (list == NULL)
{
return;
}
dfs(list->l);
dfs(list->r);
printf("->%d ", list->value);
}


50
/ \
20 30
/ \
70 80
/ \ \
10 40 60
$ cc tree29.c
$ a.out
->10->70->40->20->80->60->50->30
Depth first traversal
->10->40->70->60->80->20->30->50