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Find floor and ceil in an unsorted array
• Difficulty Level : Easy
• Last Updated : 23 Apr, 2021

Given an unsorted array arr[] and an element x, find floor and ceiling of x in arr[0..n-1].
Floor of x is the largest element which is smaller than or equal to x. Floor of x doesn’t exist if x is smaller than smallest element of arr[].
Ceil of x is the smallest element which is greater than or equal to x. Ceil of x doesn’t exist if x is greater than greates element of arr[].
Examples:

```Input : arr[] = {5, 6, 8, 9, 6, 5, 5, 6}
x = 7
Output : Floor = 6
Ceiling = 8

Input : arr[] = {5, 6, 8, 9, 6, 5, 5, 6}
x = 6
Output : Floor = 6
Ceiling = 6

Input : arr[] = {5, 6, 8, 9, 6, 5, 5, 6}
x = 10
Output : Floor = 9
Ceiling doesn't exist.```

Method 1 (Use Sorting)
1) Sort input array.
2) Use binary search to find floor and ceiling of x. Refer this and this for implementation of floor and ceiling in a sorted array.
Time Complexity : O(n log n)
Auxiliary Space : O(1)
This solution is works well if there are multiple queries of floor and ceiling on a static array. We can sort the array once and answer the queries in O(Log n) time.
Method 2 (Use Linear Search
The idea is to traverse array and keep track of two distances with respect to x.
1) Minimum distance of element greater than or equal to x.
2) Minimum distance of element smaller than or equal to x.
Finally print elements with minimum distances.

## C++

 `// C++ program to find floor and ceiling in an``// unsorted array.``#include``using` `namespace` `std;` `// Function to floor and ceiling of x in arr[]``void` `floorAndCeil(``int` `arr[], ``int` `n, ``int` `x)``{``    ``// Indexes of floor and ceiling``    ``int` `fInd, cInd;` `    ``// Distances of current floor and ceiling``    ``int` `fDist = INT_MAX, cDist = INT_MAX;` `    ``for` `(``int` `i=0; i= x && cDist > (arr[i] - x))``        ``{``        ``cInd = i;``        ``cDist = arr[i] - x;``        ``}` `        ``// If current element is closer than``        ``// previous floor.``        ``if` `(arr[i] <= x && fDist > (x - arr[i]))``        ``{``        ``fInd = i;``        ``fDist = x - arr[i];``        ``}``    ``}` `    ``if` `(fDist == INT_MAX)``    ``cout << ``"Floor doesn't exist "` `<< endl;``    ``else``    ``cout << ``"Floor is "` `<< arr[fInd] << endl;` `    ``if` `(cDist == INT_MAX)``    ``cout << ``"Ceil doesn't exist "` `<< endl;``    ``else``    ``cout << ``"Ceil is "` `<< arr[cInd] << endl;``}` `// Driver code``int` `main()``{``    ``int` `arr[] = {5, 6, 8, 9, 6, 5, 5, 6};``    ``int` `n = ``sizeof``(arr)/``sizeof``(``int``);``    ``int` `x = 7;``    ``floorAndCeil(arr, n, x);``    ``return` `0;``}`

## Java

 `// Java program to find floor and ceiling in an``// unsorted array.``import` `java.io.*;` `class` `GFG``{``     ``// Function to floor and ceiling of x in arr[]``    ``public` `static` `void` `floorAndCeil(``int` `arr[], ``int` `x)``    ``{``        ``int` `n = arr.length;``        ` `        ``// Indexes of floor and ceiling``        ``int` `fInd = -``1``, cInd = -``1``;`` ` `        ``// Distances of current floor and ceiling``        ``int` `fDist = Integer.MAX_VALUE, cDist = Integer.MAX_VALUE;`` ` `        ``for` `(``int` `i = ``0``; i < n; i++)``        ``{``            ``// If current element is closer than``            ``// previous ceiling.``            ``if` `(arr[i] >= x && cDist > (arr[i] - x))``            ``{``                ``cInd = i;``                ``cDist = arr[i] - x;``            ``}`` ` `            ``// If current element is closer than``            ``// previous floor.``            ``if` `(arr[i] <= x && fDist > (x - arr[i]))``            ``{``                ``fInd = i;``                ``fDist = x - arr[i];``            ``}``        ``}`` ` `        ``if``(fDist == Integer.MAX_VALUE)``            ``System.out.println(``"Floor doesn't exist "` `);``        ``else``            ``System.out.println(``"Floor is "` `+  arr[fInd]);`` ` `        ``if``(cDist == Integer.MAX_VALUE)``            ``System.out.println(``"Ceil doesn't exist "``);``        ``else``            ``System.out.println(``"Ceil is  "` `+ arr[cInd]);``    ``}``    ` `    ``public` `static` `void` `main (String[] args)``    ``{``        ``int` `arr[] = {``5``, ``6``, ``8``, ``9``, ``6``, ``5``, ``5``, ``6``};``        ``int` `x = ``7``;``        ``floorAndCeil(arr, x);``    ``}``}`

## Python 3

 `# Python 3 program to find``# floor and ceiling in an``# unsorted array.` `import` `sys` `# Function to floor and``# ceiling of x in arr[]``def` `floorAndCeil(arr, n, x):` `    ``# Distances of current``    ``# floor and ceiling``    ``fDist ``=` `sys.maxsize``    ``cDist ``=` `sys.maxsize` `    ``for` `i ``in` `range``(n):``    ` `        ``# If current element is closer``        ``# than previous ceiling.``        ``if` `(arr[i] >``=` `x ``and``            ``cDist > (arr[i] ``-` `x)):``        ` `            ``cInd ``=` `i``            ``cDist ``=` `arr[i] ``-` `x` `        ``# If current element is closer``        ``# than previous floor.``        ``if` `(arr[i] <``=` `x ``and` `fDist > (x ``-` `arr[i])):``        ` `            ``fInd ``=` `i``            ``fDist ``=` `x ``-` `arr[i]` `    ``if` `(fDist ``=``=` `sys.maxsize):``        ``print``(``"Floor doesn't exist "``)``    ``else``:``        ``print``(``"Floor is "` `+` `str``(arr[fInd]))` `    ``if` `(cDist ``=``=` `sys.maxsize):``        ``print``( ``"Ceil doesn't exist "``)``    ``else``:``        ``print``(``"Ceil is "` `+` `str``(arr[cInd]))` `# Driver code``if` `__name__ ``=``=` `"__main__"``:``    ``arr ``=` `[``5``, ``6``, ``8``, ``9``, ``6``, ``5``, ``5``, ``6``]``    ``n ``=` `len``(arr)``    ``x ``=` `7``    ``floorAndCeil(arr, n, x)` `# This code is contributed``# by ChitraNayal`

## C#

 `// C# program to find floor and ceiling in an``// unsorted array.``using` `System;` `class` `GFG {``    ` `    ``// Function to floor and ceiling of x in arr[]``    ``public` `static` `void` `floorAndCeil(``int` `[]arr, ``int` `x)``    ``{``        ``int` `n = arr.Length;``        ` `        ``// Indexes of floor and ceiling``        ``int` `fInd = -1, cInd = -1;` `        ``// Distances of current floor and ceiling``        ``int` `fDist = ``int``.MaxValue,``            ``cDist =``int``.MaxValue;``            ` `        ``for` `(``int` `i = 0; i < n; i++)``        ``{``            ` `            ``// If current element is closer than``            ``// previous ceiling.``            ``if` `(arr[i] >= x && cDist > (arr[i] - x))``            ``{``                ``cInd = i;``                ``cDist = arr[i] - x;``            ``}` `            ``// If current element is closer than``            ``// previous floor.``            ``if` `(arr[i] <= x && fDist > (x - arr[i]))``            ``{``                ``fInd = i;``                ``fDist = x - arr[i];``            ``}``        ``}` `        ``if``(fDist == ``int``.MaxValue)``            ``Console.Write(``"Floor doesn't exist "` `);``        ``else``            ``Console.WriteLine(``"Floor is "` `+ arr[fInd]);` `        ``if``(cDist == ``int``.MaxValue)``        ``Console.Write(``"Ceil doesn't exist "``);``        ``else``            ``Console.Write(``"Ceil is "` `+ arr[cInd]);``    ``}``    ` `    ``// Driver code``    ``public` `static` `void` `Main ()``    ``{``        ``int` `[]arr = {5, 6, 8, 9, 6, 5, 5, 6};``        ``int` `x = 7;``        ` `        ``floorAndCeil(arr, x);``    ``}``}` `// This code is contributed by nitin mittal.`

## PHP

 `= ``\$x` `&&``            ``\$cDist` `> (``\$arr``[``\$i``] - ``\$x``))``        ``{``            ``\$cInd` `= ``\$i``;``            ``\$cDist` `= ``\$arr``[``\$i``] - ``\$x``;``        ``}` `        ``// If current element``        ``// is closer than``        ``// previous floor.``        ``if` `(``\$arr``[``\$i``] <= ``\$x` `&&``            ``\$fDist` `> (``\$x` `- ``\$arr``[``\$i``]))``        ``{``            ``\$fInd` `= ``\$i``;``            ``\$fDist` `= ``\$x` `- ``\$arr``[``\$i``];``        ``}``    ``}` `    ``if` `(``\$fDist` `== 999999)``        ``echo` `"Floor doesn't "``.``             ``"exist "` `. ``"\n"` `;``    ``else``        ``echo` `"Floor is "` `.``              ``\$arr``[``\$fInd``] . ``"\n"``;` `    ``if` `(``\$cDist` `== 999999)``        ``echo` `"Ceil doesn't "` `.``             ``"exist "` `. ``"\n"``;``    ``else``        ``echo` `"Ceil is "` `.``             ``\$arr``[``\$cInd``] . ``"\n"``;``}` `// Driver code``\$arr` `= ``array``(5, 6, 8, 9,``             ``6, 5, 5, 6);``\$n` `= ``count``(``\$arr``);``\$x` `= 7;``floorAndCeil(``\$arr``, ``\$n``, ``\$x``);` `// This code is contributed``// by Sam007``?>`

## Javascript

 ``

Output :

```Floor is 6
Ceil is 8```

Time Complexity : O(n)
Auxiliary Space : O(1)
Related Articles :
Ceiling in a sorted array
Floor in a sorted array
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