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Lexicographically largest string formed from the characters in range L and R
• Difficulty Level : Basic
• Last Updated : 04 Jan, 2019

Given a string S and a range L and R, the task is to print the lexicographically largest string that can be formed from the characters in range L and R.

Examples:

```Input: str = "thgyfh", L = 2, R = 6
Output: yhhgf

Input: str = "striver", L = 3, R = 5
Output: vri
```

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

Approach:

• Iterate from min(L, R) to max(L, R) and increase the frequencies of characters in a freq[] array.
• Iterate from 25 to 0 and print the number of times every character occurs to get the lexicographically largest string.

The common point of mistake which everyone does is they iterate from L to R instead of min(L, R) to max(L, R).

Below is the implementation of the above approach:

## C++

 `// C++ program to print the``// lexicographically largest string that``// can be formed from the characters``// in range L and R`` ` `#include ``using` `namespace` `std;`` ` `// Function to return the lexicographically largest string``string printLargestString(string s, ``int` `l, ``int` `r)``{``    ``// hash array``    ``int` `freq = { 0 };`` ` `    ``// make 0-based indexing``    ``l--;``    ``r--;`` ` `    ``// iterate and count frequencies of character``    ``for` `(``int` `i = min(l, r); i <= max(l, r); i++) {``        ``freq[s[i] - ``'a'``]++;``    ``}`` ` `    ``// ans string``    ``string ans = ``""``;`` ` `    ``// iterate in frequency array``    ``for` `(``int` `i = 25; i >= 0; i--) {`` ` `        ``// add til all characters``        ``// are added``        ``while` `(freq[i]) {``            ``ans += ``char``(``'a'` `+ i);``            ``freq[i]--;``        ``}``    ``}`` ` `    ``return` `ans;``}`` ` `// Driver Code``int` `main()``{``    ``string s = ``"striver"``;``    ``int` `l = 3, r = 5;``    ``cout << printLargestString(s, l, r);``    ``return` `0;``}`

## Java

 `// Java program to print the ``// lexicographically largest String that ``// can be formed from the characters ``// in range L and R  `` ` `class` `GFG {`` ` `// Function to return the lexicographically largest String ``    ``static` `String printLargestString(String s, ``int` `l, ``int` `r) {``        ``// hash array ``        ``int` `freq[] = ``new` `int``[``26``];`` ` `        ``// make 0-based indexing ``        ``l--;``        ``r--;`` ` `        ``// iterate and count frequencies of character ``        ``for` `(``int` `i = Math.min(l, r); i <= Math.max(l, r); i++) {``            ``freq[s.charAt(i) - ``'a'``]++;``        ``}`` ` `        ``// ans String ``        ``String ans = ``""``;`` ` `        ``// iterate in frequency array ``        ``for` `(``int` `i = ``25``; i >= ``0``; i--) {`` ` `            ``// add til all characters ``            ``// are added ``            ``while` `(freq[i] > ``0``) {``                ``ans += (``char``) (``'a'` `+ i);``                ``freq[i]--;``            ``}``        ``}`` ` `        ``return` `ans;``    ``}`` ` `// Driver Code ``    ``public` `static` `void` `main(String[] args) {`` ` `        ``String s = ``"striver"``;``        ``int` `l = ``3``, r = ``5``;``        ``System.out.println(printLargestString(s, l, r));`` ` `    ``}``}``/* This JAVA code is contributed by 29AjayKumar*/`

## Python 3

 `# Python 3 program to print the``# lexicographically largest string that``# can be formed from the characters``# in range L and R`` ` `# Function to return the lexicographically ``# largest string``def` `printLargestString(s, l, r):`` ` `    ``# hash array``    ``freq ``=` `[``0``] ``*` `26`` ` `    ``# make 0-based indexing``    ``l ``-``=` `1``    ``r ``-``=` `1`` ` `    ``# iterate and count frequencies of character``    ``for` `i ``in` `range``(``min``(l, r), ``max``(l, r) ``+` `1``) :``        ``freq[``ord``(s[i]) ``-` `ord``(``'a'``)] ``+``=` `1`` ` `    ``# ans string``    ``ans ``=` `""`` ` `    ``# iterate in frequency array``    ``for` `i ``in` `range``(``25``, ``-``1``, ``-``1``):`` ` `        ``# add til all characters are added``        ``while` `(freq[i]):``            ``ans ``+``=` `chr``(``ord``(``'a'``) ``+` `i)``            ``freq[i] ``-``=` `1`` ` `    ``return` `ans`` ` `# Driver Code``if` `__name__ ``=``=` `"__main__"``:``     ` `    ``s ``=` `"striver"``    ``l ``=` `3``    ``r ``=` `5``    ``print``(printLargestString(s, l, r))`` ` `# This code is contributed by ita_c`

## C#

 `// C# program to print the lexicographically``// largest String that can be formed from the ``// characters in range L and R``using` `System;`` ` `class` `GFG``{`` ` `// Function to return the lexicographically ``// largest String ``static` `String printLargestString(String s, ``                                 ``int` `l, ``int` `r) ``{``    ``// hash array ``    ``int` `[]freq = ``new` `int``;`` ` `    ``// make 0-based indexing ``    ``l--;``    ``r--;`` ` `    ``// iterate and count frequencies``    ``// of character ``    ``for` `(``int` `i = Math.Min(l, r); ``             ``i <= Math.Max(l, r); i++)``    ``{``        ``freq[s[i] - ``'a'``]++;``    ``}`` ` `    ``// ans String ``    ``String ans = ``""``;`` ` `    ``// iterate in frequency array ``    ``for` `(``int` `i = 25; i >= 0; i--)``    ``{`` ` `        ``// add til all characters ``        ``// are added ``        ``while` `(freq[i] > 0) ``        ``{``            ``ans += (``char``) (``'a'` `+ i);``            ``freq[i]--;``        ``}``    ``}`` ` `    ``return` `ans;``}`` ` `// Driver Code ``public` `static` `void` `Main() ``{``    ``String s = ``"striver"``;``    ``int` `l = 3, r = 5;``    ``Console.Write(printLargestString(s, l, r));``}``}`` ` `// This code is contributed by 29AjayKumar`
Output:
```vri
```

Time Complexity – O(N)
Each element gets added to the frequency table only once which takes O(1) and is appended to string which also takes O(1).

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