1.2 Stack

#include <stdio.h>
#include <string.h>
#include <conio.h>

int main()
{
	char stack[30],s[30];
	int top=-1;
	int i;
	clrscr();
	printf("Enter Expression :");
	scanf("%s",&s);
	for(i=0;i<strlen(s);i++)
	{
		if( s[i]=='(' || s[i]=='{' || s[i]=='[' )
		{
			top++;
			stack[top]=s[i];
		}
		else
		{
			if((stack[top] == '(' && s[i]==')') || (stack[top]=='{' && s[i]=='}') || (stack[top]=='[' && s[i]==']'))
			{
				top--;
			}
			else
			{
				break;
			}
		}
	}
	if(top!=-1)
	{
		printf("Invalid Bracket Sequence");
	}
	else
	{
		printf("Valid Bracket Sequence");
	}
	getch();
	return 0;
}