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C Exercises: Find the minimum element in a stack

C Stack: Exercise-11 with Solution

Write a C program to find the minimum element in a stack.

Sample Solution:

C Code:

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

#define MAX_SIZE 100
int mainStack[MAX_SIZE];
int minStack[MAX_SIZE];
int top = -1;
int min_Top = -1;

void push(int element) {
    if (top >= MAX_SIZE - 1) {
        printf("Stack is full\n");
        return;
    }
    
    top++;
    mainStack[top] = element;
    
    if (min_Top == -1 || element <= minStack[min_Top]) {
        min_Top++;
        minStack[min_Top] = element;
    }
}

int pop() {
    if (top < 0) {
        printf("Stack is empty\n");
        return INT_MIN;
    }
    
    int element = mainStack[top];
    top--;
    
    if (element == minStack[min_Top]) {
        min_Top--;
    }
    
    return element;
}

int getMin() {
    if (min_Top < 0) {
        printf("Stack is empty\n");
        return INT_MIN;
    }
    
    return minStack[min_Top];
}

void printstack(int *stack)
  {
  	    printf("Current stack elements:\n");
  	    for (int i = 0; i <= top; i++) {
        printf("%d ", stack[i]);
    }

  }
int main() {
    push(9);
    push(2);
    push(4);
    push(2);
    push(4);
    printstack(mainStack);
    printf("\nMinimum element: %d\n", getMin()); 
    pop();
    pop();
    printf("\nAfter removing two elements:\n");
    printstack(mainStack);
    printf("\nMinimum element: %d\n", getMin());  
    push(1);
    printf("\nAfter adding one element:\n");
    printstack(mainStack);
    printf("\nMinimum element: %d\n", getMin());      
    return 0;
}

Sample Output: 

Current stack elements:
9 2 4 2 4 
Minimum element: 2

After removing two elements:
Current stack elements:
9 2 4 
Minimum element: 2

After adding one element:
Current stack elements:
9 2 4 1 
Minimum element: 1

Flowchart:

Flowchart: Find the minimum element in a stack.
Flowchart: Find the minimum element in a stack.
Flowchart: Find the minimum element in a stack.

C Programming Code Editor:

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Previous: Reverse a stack using push and pop.
Next: Find the maximum element in a stack.

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C Programming: Tips of the Day

C Programming - How do you pass a function as a parameter in C?

Declaration

A prototype for a function which takes a function parameter looks like the following:

void func ( void (*f)(int) );

This states that the parameter f will be a pointer to a function which has a void return type and which takes a single int parameter. The following function (print) is an example of a function which could be passed to func as a parameter because it is the proper type:

void print ( int x ) {
  printf("%d\n", x);
}

Function Call

When calling a function with a function parameter, the value passed must be a pointer to a function. Use the function's name (without parentheses) for this:

func(print);

would call func, passing the print function to it.

Function Body

As with any parameter, func can now use the parameter's name in the function body to access the value of the parameter. Let's say that func will apply the function it is passed to the numbers 0-4. Consider, first, what the loop would look like to call print directly:

for ( int ctr = 0 ; ctr < 5 ; ctr++ ) {
  print(ctr);
}

Since func's parameter declaration says that f is the name for a pointer to the desired function, we recall first that if f is a pointer then *f is the thing that f points to (i.e. the function print in this case). As a result, just replace every occurrence of print in the loop above with *f:

void func ( void (*f)(int) ) {
  for ( int ctr = 0 ; ctr < 5 ; ctr++ ) {
    (*f)(ctr);
  }
}

Ref : https://bit.ly/3skw9Um