# Compress the array into Ranges

Given an array of integers of size N, The task is to print the consecutive integers as a range.

Examples:

Input : N = 7, arr=[7, 8, 9, 15, 16, 20, 25]
Output : 7-9 15-16 20 25
Consecutive elements present are[ {7, 8, 9}, {15, 16}, {20}, {25} ]
Hence output the result as 7-9 15-16 20 25

Input : N = 6, arr=[1, 2, 3, 4, 5, 6]
Output : 1-6

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:
The problem can be easily visualised as a variation of run length encoding problem.

• First sort the array.
• Then, start a while loop for traversing the array to check the consecutive elements. The ending of the consecutive numbers will be denoted by j-1 and start by i at any particular instance.
• Increment i by 1 if it do not falls in whle loop otherwise increment it by j+1 so that it jumps to the next ith element which is out of current range.

Below is the implementation of the above approach:

## C++

 `// C++ program to compress the array ranges ` `#include ` `using` `namespace` `std; ` ` `  `// Function to compress the array ranges ` `void` `compressArr(``int` `arr[], ``int` `n) ` `{ ` `    ``int` `i = 0, j = 0; ` `    ``sort(arr, arr + n); ` `    ``while` `(i < n) { ` ` `  `        ``// start iteration from the ` `        ``// ith array element ` `        ``j = i; ` ` `  `        ``// loop until arr[i+1] == arr[i] ` `        ``// and increment j ` `        ``while` `((j + 1 < n) && ` `                 ``(arr[j + 1] == arr[j] + 1)) { ` `            ``j++; ` `        ``} ` ` `  `        ``// if the program do not enter into ` `        ``// the above while loop this means that ` `        ``// (i+1)th element is not consecutive ` `        ``// to i th element ` `        ``if` `(i == j) { ` `            ``cout << arr[i] << ``" "``; ` ` `  `            ``// increment i for next iteration ` `            ``i++; ` `        ``} ` `        ``else` `{ ` `            ``// print the consecutive range found ` `            ``cout << arr[i] << ``"-"` `<< arr[j] << ``" "``; ` ` `  `            ``// move i jump directly to j+1 ` `            ``i = j + 1; ` `        ``} ` `    ``} ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` ` `  `    ``int` `n = 7; ` `    ``int` `arr[n] = { 1, 3, 4, 5, 6, 9, 10 }; ` ` `  `    ``compressArr(arr, n); ` `} `

## Java

 `// Java program to compress the array ranges ` `import` `java.util.Arrays;  ` ` `  `class` `GFG ` `{ ` ` `  `// Function to compress the array ranges ` `static` `void` `compressArr(``int` `arr[], ``int` `n) ` `{ ` `    ``int` `i = ``0``, j = ``0``; ` `    ``Arrays.sort(arr); ` `    ``while` `(i < n)  ` `    ``{ ` ` `  `        ``// start iteration from the ` `        ``// ith array element ` `        ``j = i; ` ` `  `        ``// loop until arr[i+1] == arr[i] ` `        ``// and increment j ` `        ``while` `((j + ``1` `< n) && ` `                ``(arr[j + ``1``] == arr[j] + ``1``))  ` `        ``{ ` `            ``j++; ` `        ``} ` ` `  `        ``// if the program do not enter into ` `        ``// the above while loop this means that ` `        ``// (i+1)th element is not consecutive ` `        ``// to i th element ` `        ``if` `(i == j) ` `        ``{ ` `            ``System.out.print( arr[i] + ``" "``); ` ` `  `            ``// increment i for next iteration ` `            ``i++; ` `        ``} ` `        ``else`  `        ``{ ` `            ``// print the consecutive range found ` `            ``System.out.print( arr[i] + ``"-"` `+ arr[j] + ``" "``); ` ` `  `            ``// move i jump directly to j+1 ` `            ``i = j + ``1``; ` `        ``} ` `    ``} ` `} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main (String[] args) ` `    ``{ ` `        ``int` `n = ``7``; ` `        ``int` `arr[] = { ``1``, ``3``, ``4``, ``5``, ``6``, ``9``, ``10` `}; ` ` `  `        ``compressArr(arr, n); ` `    ``} ` `} ` ` `  `// This code is contributed by anuj_67.. `

## Python3

 `# Python program to compress the array ranges ` ` `  `# Function to compress the array ranges ` `def` `compressArr(arr, n): ` `    ``i ``=` `0``; ` `    ``j ``=` `0``; ` `    ``arr.sort(); ` `    ``while` `(i < n): ` ` `  `        ``# start iteration from the ` `        ``# ith array element ` `        ``j ``=` `i; ` ` `  `        ``# loop until arr[i+1] == arr[i] ` `        ``# and increment j ` `        ``while` `((j ``+` `1` `< n) ``and` `                ``(arr[j ``+` `1``] ``=``=` `arr[j] ``+` `1``)): ` `            ``j ``+``=` `1``; ` ` `  `        ``# if the program do not enter into ` `        ``# the above while loop this means that ` `        ``# (i+1)th element is not consecutive ` `        ``# to i th element ` `        ``if` `(i ``=``=` `j): ` `            ``print``(arr[i], end``=``" "``); ` ` `  `            ``# increment i for next iteration ` `            ``i``+``=``1``; ` `        ``else``: ` `            ``# print the consecutive range found ` `            ``print``(arr[i], ``"-"``, arr[j], end``=``" "``); ` ` `  `            ``# move i jump directly to j+1 ` `            ``i ``=` `j ``+` `1``; ` ` `  `# Driver code ` `n ``=` `7``; ` `arr ``=` `[ ``1``, ``3``, ``4``, ``5``, ``6``, ``9``, ``10` `]; ` `compressArr(arr, n); ` ` `  `# This code is contributed by PrinciRaj1992  `

## C#

 `// C# program to compress the array ranges ` `using` `System; ` ` `  `class` `GFG ` `{ ` ` `  `// Function to compress the array ranges ` `static` `void` `compressArr(``int` `[]arr, ``int` `n) ` `{ ` `    ``int` `i = 0, j = 0; ` `    ``Array.Sort(arr); ` `    ``while` `(i < n)  ` `    ``{ ` ` `  `        ``// start iteration from the ` `        ``// ith array element ` `        ``j = i; ` ` `  `        ``// loop until arr[i+1] == arr[i] ` `        ``// and increment j ` `        ``while` `((j + 1 < n) && ` `                ``(arr[j + 1] == arr[j] + 1))  ` `        ``{ ` `            ``j++; ` `        ``} ` ` `  `        ``// if the program do not enter into ` `        ``// the above while loop this means that ` `        ``// (i+1)th element is not consecutive ` `        ``// to i th element ` `        ``if` `(i == j) ` `        ``{ ` `            ``Console.Write( arr[i] + ``" "``); ` ` `  `            ``// increment i for next iteration ` `            ``i++; ` `        ``} ` `        ``else` `        ``{ ` `            ``// print the consecutive range found ` `            ``Console.Write( arr[i] + ``"-"` `+ arr[j] + ``" "``); ` ` `  `            ``// move i jump directly to j+1 ` `            ``i = j + 1; ` `        ``} ` `    ``} ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main () ` `{ ` `    ``int` `n = 7; ` `    ``int` `[]arr = { 1, 3, 4, 5, 6, 9, 10 }; ` ` `  `    ``compressArr(arr, n); ` `} ` `} ` ` `  `// This code is contributed by anuj_67.. `

Output:

```1 3-6 9-10
```

Time complexity: O(n)

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Improved By : vt_m, princiraj1992, nidhi_biet