Morse Code – Words

Decode a message from Morse code represented by consecutive 1's where each group corresponds to a letter of the alphabet

Understand the Problem

Problem Statement

Morse Code – Words: A spaceship has exploded in space and two survivors need to communicate with the station on Earth. Due to voice communication failure, they can only hear beep sounds. Each consecutive beep sound denotes an alphabet letter. For example, two consecutive beep sounds means the letter 'b'. The beep sounds are represented as 1's. Groups of consecutive 1's are given as input in each line. Help the crew decode the message.

Note: Read the input carefully to avoid errors.

Constraints

1 ≤ Number of lines ≤ 100
1 ≤ Number of 1's in a line ≤ 1000
Each group of 1's represents a single lowercase letter (a-z)
The number of consecutive 1's maps to the letter position in alphabet (1=a, 2=b, ..., 26=z)

Examples

Example 1

Input

111 1 11111111111111
1111111111111111111111111 111111111111111 111111111111111111111
11111111 11111 1 111111111111111111
1111111111111 11111

Output

can you hear me

Explanation

The first line '111 1 11111111111111' decodes to 'can' (111=3=c, 1=1=a, 11111111111111=14=n). The second line decodes to 'you', the third to 'hear', and the fourth to 'me'. Spaces between groups form words.

Example 2

Input

11 1111111 1111
1111111 111111111111 1
11111 11111111 11 1111111 11111111 111
11 11111111 1111 11111111
1 11 11 1

Output

bgd gla ehbghc bhdh abba

Explanation

Each group of 1's converts to a letter: 11=2=b, 1111111=7=g, 1111=4=d, etc. The input forms the message 'bgd gla ehbghc bhdh abba'.

Solution

#include <stdio.h>
#include <string.h>

int main() {
    char line[10000];
    int firstWord = 1;
    
    while (fgets(line, sizeof(line), stdin) != NULL) {
        int len = strlen(line);
        int count = 0;
        int firstChar = 1;
        
        if (!firstWord) {
            printf(" ");
        }
        firstWord = 0;
        
        for (int i = 0; i < len; i++) {
            if (line[i] == '1') {
                count++;
            } else if (line[i] == ' ' || line[i] == '\n' || line[i] == '\0') {
                if (count > 0) {
                    if (!firstChar) {
                        printf(" ");
                    }
                    printf("%c", count + 96);
                    count = 0;
                    firstChar = 0;
                }
            }
        }
    }
    
    return 0;
}

Time:O(n*m) where n is the number of lines and m is the average length of each line

Space:O(1) - uses a fixed-size buffer for line storage

Approach:

The C solution reads input line by line using fgets(). For each line, it iterates character by character, counting consecutive '1' characters. When it encounters a space, newline, or end of string, it converts the count to the corresponding letter using count + 96 (since ASCII 'a' is 97). Letters are printed with spaces between them, and words are separated by spaces between lines.

Key points:

Uses fgets() for safe line reading
Tracks word boundaries with firstWord flag
Converts count to letter using ASCII arithmetic
Handles multiple spaces between groups correctly

Visual Explanation

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