patternjavaMinor

Checking if all the characters from an A-Z is present in the string

Submitted by: @import:stackexchange-codereview·Mar 10, 2026·

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thepresentallcheckingcharactersfromstring

Problem

A string is said to be complete if it contains all the characters from
a to z. Given a string, check if it complete or not.

Input First line of the input contains the number of strings N. It is
followed by N lines each contains a single string.

Output For each test case print "YES" if the string is complete, else
print "NO"

Constraints 1 <= N <= 10 The length of the string is at max 100 and
the string contains only the characters a to z.

Here are the two solutions that I wrote:

class TestClass {
    private static byte N;
    public static void main(String args[] ) throws Exception {
        BufferedReader keyboard = new BufferedReader(new InputStreamReader(
                System.in));
       N = Byte.parseByte(keyboard.readLine());
        for (byte i = 0; i < N; i++) {
            String testingString = keyboard.readLine();
            isCompleteString(testingString);
        }
    }

    private static void isCompleteString(String testingString) {
        String resultString= "";
        char[] toChar = testingString.toCharArray();
        int length = toChar.length;
        for (int i = 0; i < length; i++) {
            if(resultString.indexOf(toChar[i])==-1){
                resultString=resultString.concat(toChar[i]+"");

            }

        }

        if(resultString.length()==26)System.out.println("YES");
        else System.out.println("NO");
    }

}

This took 1.6469 secs against various inputs, while this code took:

```
class TestClass {
private static byte N;
public static void main(String args[] ) throws Exception {
BufferedReader keyboard = new BufferedReader(new InputStreamReader(
System.in));
N = Byte.parseByte(keyboard.readLine());
for (byte i = 0; i < N; i++) {
String testingString = keyboard.readLine();
isCompleteString(testingString);
}
}

private static void isCompleteString(String testingString) {

char[

Solution

private static byte N;

We know that

toChar[i]+"" creates a String from each char needlessly

resultString.concat(...) creates a new String every time




You could use a

StringBuilder

 here.

But creating a

String only to measure it's length is plain wrong. You could count the char

s instead.

But counting the chars is plain wrong too. If you want to know if a beer crate is full, do you count the bottles? Or do you if there's a bottle missing?

if(resultString.length()==26)System.out.println("YES");
    else System.out.println("NO");


This should be written as

System.out.println(resultString.length()==26 ? "YES" : "NO");


apart from that 1. there should be no

resultString

, 2. there should be a method computing and a method printing.
Second version

boolean[] findingAlphabet = new boolean[26];


No good name. What about

foundChars or simply found

?

byte alphabets = (byte) toChar[i];


What byte? Never use a

byte

, unless either it's exactly what's needed or you have a big bunch of them.

findingAlphabet[122-alphabets]=true;


Nice obfuscation. What about

found[chars[i] - 'a'] = true;


? And bottle counting again

int count=0;
    for(boolean b:findingAlphabet){
        if(b)
        count++;
    }


This should be

for (boolean b : found) {
        if (!b) {
            return false;
        }
    }
    return true;


How can I optimaize these programs further (I have used BitSet)?

You haven't. But

BitSet is slower than a boolean[]

 (except when memory locality comes in play).

It looks like most of the time gets spend on IO. Not surprising, even the first solution with doing 26 times

indexOf` on a 100 chars string is not computationally intensive.

It could be sped up by avoiding strings and working with the input bytes directly. But I'd concentrate on readability first, otherwise it'll become a huge mess.

You may want to specify input encoding as US-ASCII as it's sufficient and much faster than UTF-8 which may be your platform default.

Code Snippets

private static byte N;

BufferedReader keyboard = new BufferedReader(new InputStreamReader(
            System.in));

isCompleteString(testingString);

String resultString= "";

char[] toChar = testingString.toCharArray();
    int length = toChar.length;
    for (int i = 0; i < length; i++) {

Context

StackExchange Code Review Q#91887, answer score: 4

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