CodingGyan

Number the Lines

easy Files and I/O

Problem

Print every input line with its line number in front: three digits (with leading zeros), then the character |, then the original line. Blank lines are counted and printed too (as number and |). Do not change the text of the line.

Constraints

  • 1 <= lines <= 999

Examples

Input

alpha

gamma

Output

001|alpha
002|
003|gamma

Solutions

Best approachTime O(n)Space O(n)

The position in the input gives the number. A format string pads it with zeros. The line text itself is copied without trimming.

Same code works in Java810172125Basic features only, so nothing changes between versions.
/*
 * Problem : Number the lines.
 * Input   : Several lines (blank lines allowed).
 * Output  : Numbered lines.
 * Approach: Format each line.
 * Time    : O(n)
 * Space   : O(n)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static String[] solve(String[] lines) {
        // Step 1: Count lines from 1 and format the number with three digits.
        String[] output = new String[lines.length];
        for (int i = 0; i < lines.length; i++) {
            output[i] = String.format("%03d|%s", i + 1, lines[i]);
        }
        return output;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        java.util.List<String> all = new java.util.ArrayList<>();
        while (scanner.hasNextLine()) {
            all.add(scanner.nextLine());
        }
        String[] lines = all.toArray(new String[0]);
        System.out.println(String.join("\n", solve(lines)));
    }
}
Hints (2)
  1. What does %03d do?
  2. Why must blank lines keep their number?

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