# Find distinct characters in distinct substrings of a string

Given a string str, the task is to find the count of distinct characters in all the distinct sub-strings of the given string.
Examples:

Input: str = “ABCA”
Output: 18

Hence, 1 + 2 + 3 + 3 + 1 + 2 + 3 + 1 + 2 = 18
Input: str = “AAAB”
Output: 10

Approach: Take all possible sub-strings of the given string and use a set to check whether the current sub-string has been processed before. Now, for every distinct sub-string, count the distinct characters in it (again set can be used to do so). The sum of this count for all the distinct sub-strings is the final answer.
Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach` `#include ` `using` `namespace` `std;`   `// Function to return the count of distinct` `// characters in all the distinct` `// sub-strings of the given string` `int` `countTotalDistinct(string str)` `{` `    ``int` `cnt = 0;`   `    ``// To store all the sub-strings` `    ``set items;`   `    ``for` `(``int` `i = 0; i < str.length(); ++i) {`   `        ``// To store the current sub-string` `        ``string temp = ``""``;`   `        ``// To store the characters of the` `        ``// current sub-string` `        ``set<``char``> ans;` `        ``for` `(``int` `j = i; j < str.length(); ++j) {` `            ``temp = temp + str[j];` `            ``ans.insert(str[j]);`   `            ``// If current sub-string hasn't` `            ``// been stored before` `            ``if` `(items.find(temp) == items.end()) {`   `                ``// Insert it into the set` `                ``items.insert(temp);`   `                ``// Update the count of` `                ``// distinct characters` `                ``cnt += ans.size();` `            ``}` `        ``}` `    ``}`   `    ``return` `cnt;` `}`   `// Driver code` `int` `main()` `{` `    ``string str = ``"ABCA"``;`   `    ``cout << countTotalDistinct(str);`   `    ``return` `0;` `}`

## Java

 `// Java implementation of the approach` `import` `java.util.HashSet;`   `class` `geeks` `{`   `    ``// Function to return the count of distinct` `    ``// characters in all the distinct` `    ``// sub-strings of the given string` `    ``public` `static` `int` `countTotalDistinct(String str) ` `    ``{` `        ``int` `cnt = ``0``;`   `        ``// To store all the sub-strings` `        ``HashSet items = ``new` `HashSet<>();`   `        ``for` `(``int` `i = ``0``; i < str.length(); ++i) ` `        ``{`   `            ``// To store the current sub-string` `            ``String temp = ``""``;`   `            ``// To store the characters of the` `            ``// current sub-string` `            ``HashSet ans = ``new` `HashSet<>();` `            ``for` `(``int` `j = i; j < str.length(); ++j) ` `            ``{` `                ``temp = temp + str.charAt(j);` `                ``ans.add(str.charAt(j));`   `                ``// If current sub-string hasn't` `                ``// been stored before` `                ``if` `(!items.contains(temp)) ` `                ``{`   `                    ``// Insert it into the set` `                    ``items.add(temp);`   `                    ``// Update the count of` `                    ``// distinct characters` `                    ``cnt += ans.size();` `                ``}` `            ``}` `        ``}`   `        ``return` `cnt;` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `main(String[] args) ` `    ``{` `        ``String str = ``"ABCA"``;` `        ``System.out.println(countTotalDistinct(str));` `    ``}` `}`   `// This code is contributed by` `// sanjeev2552`

## Python3

 `# Python3 implementation of the approach `   `# Function to return the count of distinct ` `# characters in all the distinct ` `# sub-strings of the given string ` `def` `countTotalDistinct(string) : `   `    ``cnt ``=` `0``; `   `    ``# To store all the sub-strings ` `    ``items ``=` `set``(); `   `    ``for` `i ``in` `range``(``len``(string)) :`   `        ``# To store the current sub-string ` `        ``temp ``=` `""; `   `        ``# To store the characters of the ` `        ``# current sub-string ` `        ``ans ``=` `set``(); ` `        ``for` `j ``in` `range``(i, ``len``(string)) :` `            ``temp ``=` `temp ``+` `string[j]; ` `            ``ans.add(string[j]); `   `            ``# If current sub-string hasn't ` `            ``# been stored before ` `            ``if` `temp ``not` `in` `items :`   `                ``# Insert it into the set ` `                ``items.add(temp); `   `                ``# Update the count of ` `                ``# distinct characters ` `                ``cnt ``+``=` `len``(ans); `   `    ``return` `cnt; `     `# Driver code ` `if` `__name__ ``=``=` `"__main__"` `: `   `    ``string ``=` `"ABCA"``; `   `    ``print``(countTotalDistinct(string)); ` `    `  `# This code is contributed by AnkitRai01`

## C#

 `// C# implementation of the approach` `using` `System;` `using` `System.Collections.Generic;`   `class` `geeks` `{`   `    ``// Function to return the count of distinct` `    ``// characters in all the distinct` `    ``// sub-strings of the given string` `    ``public` `static` `int` `countTotalDistinct(String str) ` `    ``{` `        ``int` `cnt = 0;`   `        ``// To store all the sub-strings` `        ``HashSet items = ``new` `HashSet();`   `        ``for` `(``int` `i = 0; i < str.Length; ++i) ` `        ``{`   `            ``// To store the current sub-string` `            ``String temp = ``""``;`   `            ``// To store the characters of the` `            ``// current sub-string` `            ``HashSet<``char``> ans = ``new` `HashSet<``char``>();` `            ``for` `(``int` `j = i; j < str.Length; ++j) ` `            ``{` `                ``temp = temp + str[j];` `                ``ans.Add(str[j]);`   `                ``// If current sub-string hasn't` `                ``// been stored before` `                ``if` `(!items.Contains(temp)) ` `                ``{`   `                    ``// Insert it into the set` `                    ``items.Add(temp);`   `                    ``// Update the count of` `                    ``// distinct characters` `                    ``cnt += ans.Count;` `                ``}` `            ``}` `        ``}`   `        ``return` `cnt;` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `Main(String[] args) ` `    ``{` `        ``String str = ``"ABCA"``;` `        ``Console.WriteLine(countTotalDistinct(str));` `    ``}` `}`   `// This code is contributed by 29AjayKumar`

## Javascript

 ``

Output:

`18`

Time complexity: O(n^2)

As the nested loop is used the complexity is order if n^2

Space complexity: O(n)

two sets of size n are used so the complexity would be O(2n) nothing but O(n).

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