specialStack.txt

//specialStack.h
typedef int stackElement;

typedef struct{
	int top;
	int maxSize;
	stackElement *contents; //this is our array holding our stack elements
	int min;
	int nextmin;
}stackT;

stackT* stackInit(int maxsize);
void stackPush(stackT* newStack, stackElement element);
int stackPop(stackT *newStack);
int getMin(stackT *newStack);
int peek(stackT *newStack);
int stackIsFull(stackT *newStack);
int stackIsEmpty(stackT *newStack);

//specialStack.c
#include<stdlib.h>
#include<stdio.h>
#include<limits.h>
#include "specialStack.h"

stackT* stackInit(int maxSize){
	stackT *newStack = (stackT *)malloc(sizeof(stackT));
	newStack->contents = (stackElement *)malloc(sizeof(stackElement) * maxSize);
	newStack->top = -1;
	newStack->maxSize = maxSize;
	newStack->min = INT_MAX;
	newStack->nextmin = INT_MAX;
	return newStack;
}

void stackPush(stackT *newStack, stackElement element){
	if(stackIsFull(newStack)){
		fprintf(stderr, "Stack is full! Can't push.\n");
		exit(1);
	}
	if(element < newStack->min){
		newStack->nextmin = newStack->min;
		newStack->min = element;
	}
	newStack->contents[++newStack->top] = element;
	printf("Pushed %d on the stack\n", element);
}

int stackPop(stackT *newStack){
	if(stackIsEmpty(newStack)){
		fprintf(stderr, "Stack is empty! Can't pop.\n");
		exit(1);
	}
	if(newStack->contents[newStack->top] == newStack->min)
		newStack->min = newStack->nextmin;
	return newStack->contents[newStack->top--];
}

int getMin(stackT *newStack){
	return newStack->min;
}

int peek(stackT *newStack){
	return newStack->contents[newStack->top];
}

int stackIsEmpty(stackT *newStack){
	return newStack->top == -1;
}

int stackIsFull(stackT *newStack){
	return newStack->top == newStack->maxSize-1;
}


int main(){
	stackT *newStack = stackInit(4);
	stackPush(newStack, 10);
	stackPush(newStack, 10);
	stackPush(newStack, 30);
	printf("Min element is: %d\n",getMin(newStack));
	stackPush(newStack, 5);
	printf("\nMin element is: %d\n",getMin(newStack));
	
	return 0;
}

//Makefile
CC = gcc
CFLAGS = -Wall

specialStack: specialStack.o
	$(CC) $(CFLAGS) -o specialStack specialStack.o

specialStack.o: specialStack.c specialStack.h
	$(CC) $(CFLAGS) -c specialStack.c