Finding the common characters present in all strings [closed] - c

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Compare each string and find the number of common lowercase letter in all the strings.
Each string is represented by a lowercase letter from 'a' to 'z'.
Example Input:
4
abcf
aghb
acbl
bamn
Example Output:
2 // a and b
Code:
#include<stdio.h>
#include<string.h>
int main() {
int n;
scanf("%d\n",&n);
char str[n][100];
char var[0][100];
for(int i=0; i<n; i++) { // strings
scanf("%99s/n",str[i]);
}
for(int i=0;i<100;i++) { // comparison of first 2 strings
for(int k=0;k<100;k++)
if(str[0][i]==str[1][k])
for(int j=0;j<strlen(str[0]);j++) {
var[0][j]=str[0][j]; // storing the common letters in a var array
}
}
for(int l=0; l<strlen(str[1]); l++) { // comparing letters in var array with the letters of all other strings
int x;
if(var[0][l]==str[l+2][l]);
x=strlen(var[0]); // counting the common letters
printf("%d\n",x);
}
return 0;
}

Answer 1

#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main() {
int n;
scanf("%d",&n);
char str[n][100];
char var[n][26];
memset(&var[0][0], 0, sizeof(var));
for(int i=0; i<n; i++) {
scanf("%99s", str[i]);
char ch;
for(int j=0; ch=str[i][j]; ++j){
if(islower(ch)){
var[i][ch-'a']=1;//depend on the sequence of character codes
}
}
}
int x = 0;
for(int i=0; i<26; ++i){
int num = 0;
for(int j=0;j<n;++j)
if(var[j][i])
++num;
if(num==n)//all string has character of ('a'+i)
++x;
}
printf("%d\n",x);
return 0;
}

Answer 2

Not sure why you would want to special-case the first two strings here? How about an approach like this (in pseudocode):
- create a set of characters, name it letters_in_all_strings
- add every lowercase letter to letters_in_all_strings
- for each input string
- create a set of characters, name it letters_in_this_string
- add every character in the input string to letters_in_this_string
- remove all letters from letters_in_all_strings that are not present in letters_in_this_string
- print out the size of letters_in_all_strings
You could use an array of 0s and 1s, indexed by char, to implement a set of chars in C. Or you could use glib (https://stackoverflow.com/a/2502721/2186890). Or maybe consider using a more modern programming language?