As you already know the question String Construction Hackerrank Problem
But let’s understand it in a more simple way.

A girl wants to append/join some string(character, substring) in a string that is suppose ‘p’.
but for every join, it will cost $1, but there are some good things. she can append a substring also if it will match from previous.
this means if she wants to join ‘abcbcabc’
it will cost her $5 only because she will join
a -> $1 result—-a
b -> $1 result—-ab
c -> $1 result—-abc
now she can take ‘bc’ as substring from result ‘abc’
so,
bc -> $1 result—-abcbc
now again she can take ‘abc’ as substring from result ‘abcbc’
so,
abc -> $1 result—-abcbcabc

so cost is $1+1+1+1+1=$5

if you will find a string it will reduce your cost. so help her to minimize the cost and find the cost if you will be given
the resultant string like ‘abcbcabc’
‘
Input condition

The first line contains a single integer, n, denoting the number of strings.
Each line i of the n subsequent lines contains a single string, s_i.

Limitation
1<=n<=5
1<=m<=10⁵
Subtasks

1<=m<=10³ for 45% of the maximum score.
Output condition

For each string (where 0<=i<=n), print the minimum cost of constructing string on a new line.

Input Example 

2
abcd
abab

Output Example 

4
2

if you want to learn about go to  Substring Wikipedia

Solution

#include <bits/stdc++.h>
using namespace std;

int main() {
    int t; cin >> t;
    while( t-- ) {
        string s; cin >> s;
        int M[26] = {0}, ans = 0;
        for( auto it: s ) {
            if(!M[it-'a']) {
                ans ++;
            }
            M[it-'a'] = 1;
        }
        cout << ans << "\n";
    }
    return 0;
}

#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n;
    cin >> n;
    for(int a0 = 0; a0 < n; a0++){
        string s;
        cin >> s;
        set<char> s1;
for(int i=0;i<s.length();i++)
       s1.insert(s[i]);
cout<<s1.size()<<endl;
    }
    
    return 0;
}

#!/bin/python

import sys


def ans(s):
    return len(set(s))

n = int(raw_input().strip())
for a0 in xrange(n):
    s = raw_input().strip()
    print ans(s)

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        for(int a0 = 0; a0 < n; a0++){
            String s = in.next();
            
            HashSet<Character> set = new HashSet<>();
            int cost = 0;
            for (int i = 0; i < s.length(); i++) {
                if (!set.contains(s.charAt(i))) {
                    cost++;
                    set.add(s.charAt(i));
                }
            }
            
            System.out.println(cost);
        }
    }
}