medium
1 views

Print Numbers & Ranges

Given N unique integers, print integers and integer ranges in sorted order, where consecutive integers are represented as ranges.

Understand the Problem

Problem Statement

Print Numbers & Ranges: The program must accept N unique integers as the input. The program must print the integers and the integer ranges present in the given N integers in sorted order separated by a comma as the output. The integer range must be represented by the starting value and the ending value separated by a hyphen.

Constraints

  • 2 <= N <= 100
  • 0 <= Each integer value <= 10^5
  • All integers are unique
  • Output must be comma-separated

Examples

Example 1
Input
10
1 0 25 24 3 45 2 15 4 6
Output
0-4,6,15,24-25,45
Explanation

After sorting: [0,1,2,3,4,6,15,24,25,45]. Consecutive sequences are 0-4, single 6, single 15, 24-25, single 45.

Example 2
Input
5
1 3 4 6 5
Output
1,3-6
Explanation

After sorting: [1,3,4,5,6]. Single 1, consecutive sequence 3-6.

Solution

#include <stdio.h>
#include <stdlib.h>

int compare(const void *a, const void *b) {
    return (*(int*)a - *(int*)b);
}

void printRanges(int arr[], int n) {
    qsort(arr, n, sizeof(int), compare);
    
    int i = 0;
    while (i < n) {
        int start = arr[i];
        
        // Find the end of current consecutive sequence
        while (i < n - 1 && arr[i + 1] == arr[i] + 1) {
            i++;
        }
        
        int end = arr[i];
        
        // Print range or single number
        if (start == end) {
            printf("%d", start);
        } else {
            printf("%d-%d", start, end);
        }
        
        // Print comma if not last element
        if (i < n - 1) {
            printf(",");
        }
        
        i++;
    }
    printf("\n");
}

int main() {
    int n;
    scanf("%d", &n);
    
    int arr[100];
    for (int i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }
    
    printRanges(arr, n);
    return 0;
}
Time:O(N log N)
Space:O(1)
Approach:

C Solution Explanation:

  1. Read N and the array of integers
  2. Sort array using qsort() with custom comparator
  3. Iterate through sorted array:
    • For each position, find the end of consecutive sequence by checking if next element equals current + 1
    • Print either single number or range format
    • Add comma separator (except for last element)
  4. Time complexity: O(N log N) due to sorting
  5. Space complexity: O(1) additional space

Visual Explanation

Loading diagram...
All Problems