C program for String Reversal | Samsung

Question

Write a C program for String Reversal. Print it in a reverse manner eliminating the repeated characters and spaces.

Logic

• Get the String from the user and reverse the string.
• Check for the repeated characters using checkRepeat function.
• If the element is already present skip that character or else store it in new array.
• If the element is empty space then skip that character.
• Print the new array.

Program

#include<stdio.h>
#include<string.h>
//C doesn't support bool so we convert int as bool by using typedef
typedef int bool;
#define true 1
#define false 0
bool checkRepeat(char arr[],int find)
{
    int i, len = strlen(arr);
    bool flag = false;
    for(i = 0; i< len ; i++)
    {
        if( find == arr[i])
          {
             flag = true;           //Variable already present in array
             printf("%d",i);
          }

    }
    return flag;
}
int main()
{
    char arr[20],arr2[20], ch;
    bool flag;
    gets(arr);
    //don't use scanf("%s",&arr) cuz it stops when encounter a space
    int i,j,len = strlen(arr);
     j = len-1;
     /*Reversing the string*/
    for(i = 0;i< len/2; i++)
    {
        ch = arr[i];
        arr[i] = arr[j];
        arr[j] = ch;
        j--;
    }
    arr2[0] = arr[0];
    j = 1;
    for(i = 1; i<len; i++)
    {
        if(arr[i] == ' ')
            continue;                   //Skip if space
        flag = checkRepeat(arr2, arr[i]);
        if(!flag)                       //If not a repeating variable
        {
            arr2[j] = arr[i];
            j++;
        }
    }

    printf("\n%s", arr2);
    return 0;

}

Analysis

Time complexity is O(n), here n is the length of the input.

Space complexity is O(n), here n is the length of the input.

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