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#include #include #include

typedef struct stack_node{ int data; struct stack_node* next;

}node;

void push(node **head_ref,int data);int pop(node **head_ref);int peek(node *head);int IsEmpty(node *head);void reverse_string(char *s);void conv_to_postfix(char *s);int ischar(char c);int close(char c);int open(char c);

int main(void){ int val; node *head=NULL; char s[]="VISHY"; char exp[]="a+b-c+d"; val=IsEmpty(head); if(val!=0) printf("Stack is empty\n"); else printf("Stack is full\n"); push(&head,10); push(&head,20); push(&head,30); printf("%d popped from stack\n",pop(&head));

printf("Top element of the stack: %d\n",peek(head)); reverse_string(s); printf("Reversed String: %s\n",s); conv_to_postfix(exp); printf("Postfix exp: %s\n",exp); return 0;}

void push(node **head_ref,int data){ node *new_node=(node *)malloc(sizeof(node)); new_node->data=data;

new_node->next=*head_ref; *head_ref=new_node; printf("%d pushed on to stack\n",data);}

int pop(node **head_ref){ if(*head_ref==NULL) return INT_MIN; int data=(*head_ref)->data; node *temp=*head_ref; *head_ref=(*head_ref)->next; free(temp); return data;

}

int peek(node *head)

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{ if(head==NULL) return INT_MIN; return head->data;}

int IsEmpty(node *head){

if(head==NULL) return 1; return 0;}

void reverse_string(char *s){ node *head=NULL; int i; for(i=0;s[i];++i) push(&head,s[i]); i=0; while(!IsEmpty(head)) s[i++]=pop(&head);

}

void conv_to_postfix(char *s){ int i,j; char *q=(char *)malloc(sizeof(s)); node *head=NULL; for(i=0,j=0;s[i];++i) { if(ischar(s[i])) { q[j]=s[i]; ++j;

} else if(close(s[i])) while(!open(s[i])) q[j++]=pop(&head); else push(&head,s[i]); } while(!IsEmpty(head)) q[j++]=pop(&head); q[j]='\0'; for(i=0;q[i];++i) s[i]=q[i];}

int ischar(char c){ if(c>='a' && c