C Exercises: Read a list of pairs of a word and a page number, and prints the word and a list of the corresponding page numbers

C Basic Declarations and Expressions: Exercise-149 with Solution

Group words by page numbers

Write a C program that 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 appears in a page more than once. The words should be printed in alphabetical order and the page numbers should be printed in ascending order.

Input:
word page_number
Output:
word
a_list_of_the_page_number
word
a_list_of_the_Page_number

Sample Solution:

C Code:

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

// Define a structure to hold a word and its corresponding page number
typedef struct{
  int page_no;
  char word[50];
} STR;

main(){
  STR temp, str[10000]; // Declare variables of type STR
  int i=0,j,k;
  int count=0;

  // Prompt user for input
  printf("Input pairs of a word and a page_no number:\n"); 

  // Read word and page_no pairs until end of file (EOF)
  while(scanf("%s %d",str[i].word,&str[i].page_no)!=EOF){
    i++;
  }

  // Sorting algorithm to sort words alphabetically and by page number if words are the same
  for(j=0;j<i;j++){
    for(k=i-1;0<k;k--){
      if(strcmp(str[k].word,str[k-1].word)<0){
        temp=str[k];
        str[k]=str[k-1];
        str[k-1]=temp;
      }
      else if(strcmp(str[k].word,str[k-1].word)==0){
        if(str[k].page_no<str[k-1].page_no){
          temp=str[k];
          str[k]=str[k-1];
          str[k-1]=temp;
        }
      }
    }
  }

  // Print sorted word and page number pairs
  printf("\nWord and page_no number in alphabetical order:\n"); 
  for(j=0;j<i;j++){
    if(j!=0){
      if(strcmp(str[j].word,str[j-1].word)==0){
        printf(" %d",str[j].page_no);
      }
      else{
        printf("\n%s\n%d",str[j].word,str[j].page_no);
      }
    }
    else{
      printf("%s\n%d",str[j].word,str[j].page_no);
    }
  }

  printf("\n");
  return 0;
}

Sample Output:

Input pairs of a word and a page_no number:
Twinkle
65
Twinkle
55
Little
25
Star
35
^Z

Word and page_no number in alphabetical order:
Little
25
Star
35
Twinkle
55 65

Flowchart:

C programming Code Editor:

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