#include<stdio.h>
char * longestPalindrome();
int main(){
  int n;
  scanf("%d",&n);
  char arr[n];
  scanf("%s",arr);
  printf("%s",longestPalindrome(arr));
}
char * longestPalindrome(char * s){
    int size=0,k,x,y,low=0,high=0,state,count=1;
for(int i=0;s[i]!='\0';i++){
    size++;
}
    for(int i=0;i<size;i++){
        if(count==1)
            k=i+1;
        if(k==size)
            break;
        count=0;
        state=0;
        if(s[i]==s[k] && (high-low)<(k-i)){
            x=i,y=k;
            while(x<y){
                if(s[x]==s[y]){
                    x++;
                    y--;
                }
                else{
                    state=1;
                    break;
                }
            }
            if(state==0){
                if((high-low)<(k-i)){
                    high=k;
                    low=i;
                }
            }
        }
        k++;
        if(k==size){
            count=1;
        }
        else{
            i--;
        }
    }
    char *a=(char *)malloc(sizeof((high-low+1)*sizeof(char)));
    for(int i=low;i<=high;i++){
        a[i-low]=s[i];
    }
    return a;
}
by

C Language online compiler

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Read inputs from stdin

OneCompiler's C online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}