PHP Exercises: Reads a list of pairs of a word and a page number, and prints the word and a list of the corresponding page numbers

Last update on April 19 2025 11:50:23 (UTC/GMT +8 hours)

77. Word and Page Number Indexing

Write a PHP program which reads a list of pairs of a word and a page number, and prints the word and a list of the corresponding page numbers.
The number of pairs of a word and a page number is less than or equal to 1000. A word never appear in a page more than once. The words should be printed in alphabetical order and the page numbers should be printed in ascending order.

Sample Output:
The maximum value of the sum of integers passing according to the rule on one line.

Sample Solution:

PHP Code:

<?php
// Initialize an empty array to store page numbers associated with words
$page = array();

// Continuously read lines from standard input until there are no more lines
while($line = fgets(STDIN)){
    // Extract word and page number from the line
    list($a, $b) = explode(" ", trim($line));

    // Check if the word is already in the array, if not, initialize an empty array for it
    if(!isset($page[$a])){
        $page[$a] = array();
    }

    // Add the page number to the array associated with the word
    $page[$a][] = $b;
} 

// Sort the array based on the keys (words)
ksort($page);

// Display a message indicating the output format
echo "The word and a list of the corresponding page numbers:\n";

// Iterate through each word and associated array of page numbers
foreach($page as $word => $arr){
    // Sort the array of page numbers in ascending order
    sort($arr, SORT_NUMERIC);

    // Display the word followed by a newline
    echo $word."\n";

    // Display the sorted list of page numbers separated by spaces followed by a newline
    echo implode($arr, " ")."\n";
}

?>

Explanation:

Initialize Page Tracking Array:

Creates an empty array $page to store page numbers associated with each word.

Read Input Lines Continuously:

Reads lines from standard input until no more lines are available.

Extract Word and Page Number:

For each line, splits the line into $a (word) and $b (page number) by a space.

Store Page Numbers for Each Word:

Checks if the word ($a) already exists in $page.
If it doesn't, initializes an empty array for that word.
Adds the page number ($b) to the word's array in $page.

Sort Words Alphabetically:

Sorts $page by keys (words) in ascending order using ksort().

Display the Word-Page Mapping:

Prints a message indicating the output format: "The word and a list of the corresponding page numbers:".

Iterates through each word in $page:

Sorts its page numbers array in ascending order.
Prints the word.
Prints the sorted page numbers for that word, separated by spaces.

Sample Input:
apple 5
banana 6

Sample Output:

The word and a list of the corresponding page numbers:
apple
5
banana
6

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to read a list of word-page pairs and print an index with each word followed by sorted page numbers.
Write a PHP script to merge duplicate words with their corresponding page numbers and display a combined index.
Write a PHP script to organize a series of word-page pairs alphabetically and output the list with page numbers in ascending order.
Write a PHP script to group input words with multiple page references and display them in an indexed format.

PHP Code Editor:

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