C language bracket matching (stack bracket matching C language)

Hello everyone , I meet you again , I'm your friend, Quan Jun .

Given a string of characters , No more than 100 Characters , May include parentheses 、 Numbers 、 Letter 、 Punctuation 、 Space , Program to check the... In this string of characters ( ) ,[ ],{ } match .

Input format : The input gives a line of string in one line , No more than 100 Characters , May include parentheses 、 Numbers 、 Letter 、 Punctuation 、 Space .

Output format : If parentheses are paired , Output yes, Otherwise output no.

sample input 1: sin(10+20) sample output 1: yes sample input 2: {[}] sample output 2: no

Ideas ： Enter some strings for the title , Let's keep parentheses first , Judge whether it matches . If you encounter the left bracket , It into the stack , If you encounter a closing bracket , Compare it with the top element , If the match , Out of the stack , Continue to repeat the operation , Until the string is gone . In case of mismatched bracket pairs during the period, it will be output directly no , If the stack is empty , Description matches , It outputs yes.

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

int left(char c)// Determine whether it is an open bracket , Is to return 1, No return 0.
{ 
   
    if(c=='('||c=='{'||c=='[')
    { 
   
        return 1;
    }
    else
    { 
   
        return 0;
    }
}

int right(char c)// Determine whether it is a right parenthesis , Is to return 1, No return 0.
{ 
   
    if(c==')'||c=='}'||c==']')
    { 
   
        return 1;
    }
    else
    { 
   
        return 0;
    }
}

int check(char left,char right)// Determine whether the left and right parentheses match , Is to return 1, No return 0.
{ 
   
    if(left=='('&&right==')')
    { 
   
        return 1;
    }
    
    if(left=='{'&&right=='}')
    { 
   
        return 1;
    }
    
    if(left=='['&&right==']')
    { 
   
        return 1;
    }
    
    return 0;
}

int main()// The main function .
{ 
   
    int i=0,l;// Define loop variables i And string length l.
    char stack[200];// Define the character array to store the left parenthesis .
    int top=0;// Initialization stack , The stack is empty. , To the top of the stack top=0;
    char s[200];// Store string .
    gets(s);// Enter a string to s Array , In addition to storing strings in the array , It is also stored at the end “/0”, Is a string .
    l=strlen(s);// String length .
    
    for(i=0;i<l;i++)// Traverse the characters in each string .
    { 
   
        if(left(s[i])==1)// If it is an open bracket, put it on the stack , At the same time, the top of the stack moves upward .
        { 
   
            stack[top]=s[i];
            top++;
        }
        else if(right(s[i])==1)// If it's right bracket , Then start judging whether it matches in the stack .
        { 
   
            if(check(stack[top-1],s[i]))// If the match , Then move the top of the stack down , Continue with the next new for loop .
            { 
   
                top--;
                continue;
            }
            else// If it doesn't match , Then output no, Program return 0, end .
            { 
   
                printf("no");
                return 0;
            }
        }
    }
    // If not in for End of cycle , Then you need to judge whether the stack is empty . Because it's not for End of cycle , The description is matched successfully , But there will be special situations, such as （（（））, Make the stack not empty . Therefore, whether the brackets match successfully depends not only on whether the right bracket has the left bracket to match , You also need to determine whether the stack is empty .
    if(top==0)
    { 
   
      printf("yes");
      return 0;
    }
    else
    { 
   
    printf("no");
    return 0;
    }
   
}

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