Answer to Question #159333 in C for Zenifer

Question

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

Open brackets must be closed by the same type of brackets.

Open brackets must be closed in the correct order.

Example 1:

Input: s = "()"

Output: true

Example 2:

Input: s = "()[]{}"

Output: true

Example 3:

Input: s = "(]"

Output: false

Example 4:

Input: s = "([)]"

Output: false

Example 5:

Input: s = "{[]}"

Output: true

*Your program output should follow the example in the instruction.

* The program should print the input parentheses and the output (true/false).                                                                     

*Parentheses.txt : ((()))

Please Follow this Program to Solve the Parentheses:

#include <stdio.h>

#include <string.h>

#define mx 1000000 //max size of 10^6

int str_sz;

char str[mx];

int stk_sz;

char stack[mx];

int checker() {

  stk_sz = 0;

  for (int i = 0; i < str_sz; i++) {

    if (str[i] == '(' || str[i] == '{' || str[i] == '[') { //if there is an opening bracket

      //push it on the stack

      stack[stk_sz] = str[i];

      stk_sz++;

    } else {

      if (stk_sz == 0) return 0; //if stack is empty, return 0

      switch (str[i]) {

      case ')':

        if (stack[stk_sz - 1] != '(') return 0;

        stk_sz--;

        break;

      case '}':

        if (stack[stk_sz - 1] != '{') return 0;

        stk_sz--;

        break;

      case ']':

        if (stack[stk_sz - 1] != '[') return 0;

        stk_sz--;

        break;

      }

    }

  }

  if (stk_sz > 0) return 0; //if stack is not empty, return 0

  return 1;

}

int main() {

  scanf("%s", str);

  str_sz = strlen(str);

  if (str_sz == 0) {

    puts("String is empty");

    return 0;

  }

  if (checker()) puts("Balanced");

  else puts("Not balanced");

}

You are required to complete this Parentheses program template I provide and use the stack to solve the problem. Please test the program.

#include <stdio.h>

#include <stdlib.h>

// This is where the parentheses are stored in memory

char buffer[1024];

char stack_pop();

void stack_push(char ch);

int stack_size();

int main(){

FILE *fp;

  // The parentheses sequences is in the parentheses.txt file.

  fp=fopen("parentheses.txt","r");

  if(fp==NULL){

  printf("The input file does not exist.\n");

  exit(-1);

  }

  // Read the parenthese sequences into buffer array.

  fgets(buffer,1024,fp);

  //printf("%s",buffer);

}

// The pop operation in the stack. To be done.

char stack_pop(){

return ')';

}

// The push operation in the stack. To be done.

void stack_push(char ch){

}

// The number of elements in the stack. To be done.

int stack_size(){

return 0;

}

Answer 1

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


// This is where the parentheses are stored in memory
char buffer[1024];
char stack_pop();
void stack_push(char ch);
int stack_size();


int main(int argc, char* argv[]){
    FILE *fp;
    char *pch;
    char ch;
    int correct = 1;
    
    // The parentheses sequences is in the parentheses.txt file.
    if (argc > 1) {
        fp=fopen(argv[1],"r");
    }
    else {
        fp=fopen("parentheses.txt","r");
    }
    if(fp==NULL){
        printf("The input file does not exist.\n");
        exit(-1);
    }

    // Read the parenthese sequences into buffer array.

    fgets(buffer,1024,fp);
    printf("Input: s = \"%s\"\n",buffer);
    
    for (pch = buffer; *pch != '\0'; pch++ ) {
        if (*pch == '(' || *pch == '[' || *pch == '{') {
            stack_push(*pch);
        }
        else if (stack_size() == 0 ) {
            correct = 0;
            break;
        }
        else {
            ch = stack_pop();
            if (ch == '(' && *pch != ')') {
                correct = 0;
                break;
            }
            if (ch == '[' && *pch != ']') {
                correct = 0;
                break;
            }
            if (ch == '{' && *pch != '}') {
                correct = 0;
                break;
            }
        }
    }
    
    if (correct) {
        printf("Output: true\n");
    }
    else {
        printf("Output: false\n");
    }

    return 0;
}


char stack[1024];
int top=0;
// The pop operation in the stack. To be done.
char stack_pop(){
    return stack[--top];
}

// The push operation in the stack. To be done.
void stack_push(char ch){
    stack[top++] = ch;
}

// The number of elements in the stack. To be done.
int stack_size(){
    return top;
}