# For each element in 1st array count elements less than or equal to it in 2nd array | Set 2

Given two unsorted arrays arr1[] and arr2[]. They may contain duplicates. For each element in arr1[] count elements less than or equal to it in array arr2[].

Examples:

```Input : arr1[] = [1, 2, 3, 4, 7, 9]
arr2[] = [0, 1, 2, 1, 1, 4]
Output : [4, 5, 5, 6, 6, 6]

Input : arr1[] = [5, 10, 2, 6, 1, 8, 6, 12]
arr2[] = [6, 5, 11, 4, 2, 3, 7]
Output : [4, 6, 1, 5, 0, 6, 5, 7]
```

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

This problem is already discussed in the previous post. In this article, a more optimized linear time solution to the above problem is discussed. The approach discussed here works for arrays with values in small range. A range of values that can be used as index in an array.

The idea is to use an array to create a direct address table initially filled with zero, such that hash[i] gives the count of an element in the second array arr2[]. Now, calculate pre-sum of the hash array. Doing this, hash[i] will now give the count of elements less than or equal to in second array arr2[].

Now, traverse the first array and print hash[arr1[i]].

Below program illustrate the above approach:

## C++

 `// C++ program for each element in 1st  ` `// array count elements less than or equal to it  ` `// in 2nd array  ` ` `  `#include   ` `using` `namespace` `std;  ` ` `  `#define MAX 100000  ` ` `  `// Function for each element in 1st  ` `// array count elements less than or equal to it  ` `// in 2nd array  ` `void` `countEleLessThanOrEqual(``int` `arr1[], ``int` `m,  ` `                                ``int` `arr2[], ``int` `n)  ` `{  ` `    ``// Creating hash array initially  ` `    ``// filled with zero  ` `    ``int` `hash[MAX] = {0};  ` `     `  `    ``// Insert element of arr2[] to hash  ` `    ``// such that hash[i] will give count of  ` `    ``// element i in arr2[]  ` `    ``for` `(``int` `i = 0; i < n; i++)  ` `        ``hash[arr2[i]]++;  ` ` `  `    ``// Presum of hash array  ` `    ``// such that hash[i] will give count of  ` `    ``// element less than or equals to i in arr2[]  ` `    ``for` `(``int` `i=1; i

## Java

 `// Java program for each element  ` `// in 1st array count elements  ` `// less than or equal to it in  ` `// 2nd array  ` `import` `java.io.*; ` ` `  `class` `GFG  ` `{ ` `static` `int` `MAX = ``100000``; ` ` `  `// Function for each element  ` `// in 1st array count elements  ` `// less than or equal to it  ` `// in 2nd array  ` `static` `void` `countEleLessThanOrEqual(``int` `arr1[], ``int` `m,  ` `                                    ``int` `arr2[], ``int` `n) ` `{  ` `    ``// Creating hash array initially ` `    ``// filled with zero ` `    ``int` `hash[] = ``new` `int``[MAX]; ` `     `  `    ``// Insert element of arr2[] to ` `    ``// hash such that hash[i] will ` `    ``// give count of element i in arr2[] ` `    ``for` `(``int` `i = ``0``; i < n; i++) ` `        ``hash[arr2[i]]++; ` ` `  `    ``// Presum of hash array ` `    ``// such that hash[i] will  ` `    ``// give count of element  ` `    ``// less than or equals to  ` `    ``// i in arr2[] ` `    ``for``(``int` `i = ``1``; i < MAX; i++) ` `    ``{ ` `        ``hash[i] = hash[i] +  ` `                  ``hash[i - ``1``]; ` `    ``} ` `     `  `    ``// Traverse arr1[] and  ` `    ``// print hash[arr[i]] ` `    ``for` `(``int` `i = ``0``; i < m; i++)  ` `    ``{ ` `        ``System.out.print(hash[arr1[i]] + ``" "``); ` `    ``} ` `} ` ` `  `// Driver code ` `public` `static` `void` `main (String[] args)  ` `{ ` `    ``int` `arr1[] = {``1``, ``2``, ``3``, ``4``, ``7``, ``9``}; ` `    ``int` `arr2[] = {``0``, ``1``, ``2``, ``1``, ``1``, ``4``}; ` `    ``int` `m, n; ` `     `  `    ``m = arr1.length; ` `    ``n = arr2.length; ` `     `  `    ``countEleLessThanOrEqual(arr1, m, arr2, n); ` `} ` `} ` ` `  `// This code is contributed ` `// by inder_verma `

## Python3

 `# Python 3 program for each element in 1st  ` `# array count elements less than or equal  ` `# to it in 2nd array  ` ` `  `MAX` `=` `100000` ` `  `# Function for each element in 1st  ` `# array count elements less than or  ` `# equal to it in 2nd array  ` `def` `countEleLessThanOrEqual(arr1, m, arr2, n): ` `     `  `    ``# Creating hash array initially  ` `    ``# filled with zero  ` `    ``hash` `=` `[``0` `for` `i ``in` `range``(``MAX``)]  ` `     `  `    ``# Insert element of arr2[] to hash  ` `    ``# such that hash[i] will give count  ` `    ``# of element i in arr2[]  ` `    ``for` `i ``in` `range``(n): ` `        ``hash``[arr2[i]] ``+``=` `1` ` `  `    ``# Presum of hash array such that  ` `    ``# hash[i] will give count of element  ` `    ``# less than or equals to i in arr2[]  ` `    ``for` `i ``in` `range``(``1``, ``MAX``, ``1``): ` `        ``hash``[i] ``=` `hash``[i] ``+` `hash``[i ``-` `1``]  ` `     `  `    ``# Traverse arr1[] and print hash[arr[i]]  ` `    ``for` `i ``in` `range``(m): ` `        ``print``(``hash``[arr1[i]], end ``=` `" "``)      ` ` `  `# Driver code  ` `if` `__name__ ``=``=` `'__main__'``: ` `    ``arr1 ``=` `[``1``, ``2``, ``3``, ``4``, ``7``, ``9``]  ` `    ``arr2 ``=` `[``0``, ``1``, ``2``, ``1``, ``1``, ``4``]  ` `    ``m ``=` `len``(arr1)  ` `    ``n ``=` `len``(arr2) ` `     `  `    ``countEleLessThanOrEqual(arr1, m, arr2, n)  ` `     `  `# This code is contributed by ` `# Shashank_Sharma `

## C#

 `// C# program for each element  ` `// in 1st array count elements  ` `// less than or equal to it in  ` `// 2nd array  ` `using` `System; ` `public` `class` `GFG {  ` ` `  `static` `int` `MAX = 100000;  ` ` `  `// Function for each element  ` `// in 1st array count elements  ` `// less than or equal to it  ` `// in 2nd array  ` `static` `void` `countEleLessThanOrEqual(``int` `[]arr1, ``int` `m,  ` `                                    ``int` `[]arr2, ``int` `n)  ` `{  ` `    ``// Creating hash array initially  ` `    ``// filled with zero  ` `    ``int` `[]hash = ``new` `int``[MAX];  ` `     `  `    ``// Insert element of arr2[] to  ` `    ``// hash such that hash[i] will  ` `    ``// give count of element i in arr2[]  ` `    ``for` `(``int` `i = 0; i < n; i++)  ` `        ``hash[arr2[i]]++;  ` ` `  `    ``// Presum of hash array  ` `    ``// such that hash[i] will  ` `    ``// give count of element  ` `    ``// less than or equals to  ` `    ``// i in arr2[]  ` `    ``for``(``int` `i = 1; i < MAX; i++)  ` `    ``{  ` `        ``hash[i] = hash[i] +  ` `                ``hash[i - 1];  ` `    ``}  ` `     `  `    ``// Traverse arr1[] and  ` `    ``// print hash[arr[i]]  ` `    ``for` `(``int` `i = 0; i < m; i++)  ` `    ``{  ` `        ``Console.Write(hash[arr1[i]] + ``" "``);  ` `    ``}  ` `}  ` ` `  `// Driver code  ` `public` `static` `void` `Main ()  ` `{  ` `    ``int` `[]arr1 = {1, 2, 3, 4, 7, 9};  ` `    ``int` `[]arr2 = {0, 1, 2, 1, 1, 4};  ` `    ``int` `m, n;  ` `     `  `    ``m = arr1.Length;  ` `    ``n = arr2.Length;  ` `     `  `    ``countEleLessThanOrEqual(arr1, m, arr2, n);  ` `}  ` `}  ` ` `  ` `  `     `  `// This code is contributed by Shikha Singh.  `

## PHP

 ` `

Output:

```4 5 5 6 6 6
```

Another method:(Using vector and map)

 `// C++ program for each element in 1st  ` `// array count elements less than or equal to it  ` `// in 2nd array  ` `#include ` `#include ` `#include ` ` `  `// Function for each element in 1st  ` `// array count elements less than or equal to it  ` `// in 2nd array  ` `void` `countLessThanOrEqual(``const` `std::vector<``int``>& vec1,  ` `                        ``const` `std::vector<``int``>& vec2) { ` `    ``std::map<``int``, unsigned ``int``> countOfVec2; ` `    ``for` `(``const` `auto``& item : vec2) { ` `        ``++countOfVec2[item]; ` `    ``} ` ` `  `    ``unsigned ``int` `prev = 0; ` `    ``for` `(``auto``& pair : countOfVec2) { ` `        ``pair.second += prev; ` `        ``prev = pair.second; ` `    ``} ` `    ``// Traverse arr1[] and print result  ` `    ``for` `(``const` `auto``& item : vec1) { ` `        ``unsigned ``int` `result = (--countOfVec2.upper_bound(item))->second; ` `        ``std::cout << result << ``" "``; ` `    ``} ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``std::vector<``int``> arr1 = { 1, 2, 3, 4, 7, 9 }; ` `    ``std::vector<``int``> arr2 = { 0, 1, 2, 1, 1, 4 }; ` ` `  `    ``countLessThanOrEqual(arr1, arr2); ` ` `  `    ``return` `0; ` `} `

Output:

```4 5 5 6 6 6
```

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