# Find the Substring with maximum product

Given a string str containing only lowercase English alphabets of size N, the task is to find the substring having the maximum product.

Each English alphabet has a value such that val(‘a’) = 0, val(‘b’) = 1, val(‘c’) = 2, ……, val(‘z’) = 25.

Examples:

Input: str = “sdtfakdhdahdzz”
Output: hdzz
Here, the maximum product is for the substring “hdzz”.
product = 7 * 3 * 25 * 25 = 13125

Input: str = “geeksforgeeks”
Output: geeksforgeeks

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

Approach:

• First, traverse through the given string while maintaining a maximum product value.
• Product will always keep increasing or will remain constant unless we encounter an ‘a’. Hence, start a new substring after each ‘a’ occurrence.
• Also, along with the maximum product value we will also maintain the substring to which the maximum product corresponds.
• Once the entire string has been traversed, print the substring corresponding to the maximum product.

Below is the implementation of the above approach:

## C++

 `// C++ program to find the maximum product substring ` ` `  `#include ` `using` `namespace` `std; ` ` `  `// Function to return the value of a character ` `int` `value(``char` `x) ` `{ ` `    ``return` `(``int``)(x - ``'a'``); ` `} ` ` `  `// Function to find the maximum product substring ` `string maximumProduct(string str, ``int` `n) ` `{ ` `    ``// To store substrings ` `    ``string answer = ``""``, curr = ``""``; ` `    ``long` `long` `maxProduct = 0, product = 1; ` ` `  `    ``for` `(``int` `i = 0; i < n; i++) { ` `        ``product *= 1LL * value(str[i]); ` ` `  `        ``curr += str[i]; ` ` `  `        ``// Check if current product is maximum ` `        ``// possible or not ` `        ``if` `(product >= maxProduct) { ` `            ``maxProduct = product; ` `            ``answer = curr; ` `        ``} ` ` `  `        ``// If product is 0 ` `        ``if` `(product == 0) { ` `            ``product = 1; ` `            ``curr = ``""``; ` `        ``} ` `    ``} ` ` `  `    ``// Return the substring with maximum product ` `    ``return` `answer; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``string str = ``"sdtfakdhdahdzz"``; ` ` `  `    ``int` `n = str.size(); ` ` `  `    ``// Function call ` `    ``cout << maximumProduct(str, n) << endl; ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to find the maximum product subString ` ` `  `class` `GFG{ ` `  `  `// Function to return the value of a character ` `static` `int` `value(``char` `x) ` `{ ` `    ``return` `(``int``)(x - ``'a'``); ` `} ` `  `  `// Function to find the maximum product subString ` `static` `String maximumProduct(String str, ``int` `n) ` `{ ` `    ``// To store subStrings ` `    ``String answer = ``""``, curr = ``""``; ` `    ``long` `maxProduct = ``0``, product = ``1``; ` `  `  `    ``for` `(``int` `i = ``0``; i < n; i++) { ` `        ``product *= 1L * value(str.charAt(i)); ` `  `  `        ``curr += str.charAt(i); ` `  `  `        ``// Check if current product is maximum ` `        ``// possible or not ` `        ``if` `(product >= maxProduct) { ` `            ``maxProduct = product; ` `            ``answer = curr; ` `        ``} ` `  `  `        ``// If product is 0 ` `        ``if` `(product == ``0``) { ` `            ``product = ``1``; ` `            ``curr = ``""``; ` `        ``} ` `    ``} ` `  `  `    ``// Return the subString with maximum product ` `    ``return` `answer; ` `} ` `  `  `// Driver code ` `public` `static` `void` `main(String[] args) ` `{ ` `    ``String str = ``"sdtfakdhdahdzz"``; ` `  `  `    ``int` `n = str.length(); ` `  `  `    ``// Function call ` `    ``System.out.print(maximumProduct(str, n) +``"\n"``); ` `  `  `} ` `} ` ` `  `// This code is contributed by 29AjayKumar `

## Python3

 `# Python3 program to find the maximum product sub ` ` `  `# Function to return the value of a character ` `def` `value(x): ` `    ``return` `(``ord``(x) ``-` `ord``(``'a'``)) ` ` `  `# Function to find the maximum product sub ` `def` `maximumProduct(strr, n): ` ` `  `    ``# To store subs ` `    ``answer ``=` `"" ` `    ``curr ``=` `"" ` `    ``maxProduct ``=` `0` `    ``product ``=` `1` ` `  `    ``for` `i ``in` `range``(n): ` `        ``product ``*``=``value(strr[i]) ` ` `  `        ``curr ``+``=` `strr[i] ` ` `  `        ``# Check if current product is maximum ` `        ``# possible or not ` `        ``if` `(product >``=` `maxProduct): ` `            ``maxProduct ``=` `product ` `            ``answer ``=` `curr ` ` `  `        ``# If product is 0 ` `        ``if` `(product ``=``=` `0``): ` `            ``product ``=` `1` `            ``curr ``=` `"" ` ` `  `    ``# Return the sub with maximum product ` `    ``return` `answer ` ` `  `# Driver code ` `if` `__name__ ``=``=` `'__main__'``: ` `    ``strr ``=` `"sdtfakdhdahdzz"` ` `  `    ``n ``=` `len``(strr) ` ` `  `    ``# Function call ` `    ``print``(maximumProduct(strr, n)) ` ` `  `# This code is contributed by mohit kumar 29 `

## C#

 `// C# program to find the maximum product subString ` ` `  `using` `System; ` ` `  `public` `class` `GFG{ ` ` `  `// Function to return the value of a character ` `static` `int` `value(``char` `x) ` `{ ` `    ``return` `(``int``)(x - ``'a'``); ` `} ` ` `  `// Function to find the maximum product subString ` `static` `String maximumProduct(String str, ``int` `n) ` `{ ` `    ``// To store subStrings ` `    ``String answer = ``""``, curr = ``""``; ` `    ``long` `maxProduct = 0, product = 1; ` ` `  `    ``for` `(``int` `i = 0; i < n; i++) { ` `        ``product *= 1L * value(str[i]); ` ` `  `        ``curr += str[i]; ` ` `  `        ``// Check if current product is maximum ` `        ``// possible or not ` `        ``if` `(product >= maxProduct) { ` `            ``maxProduct = product; ` `            ``answer = curr; ` `        ``} ` ` `  `        ``// If product is 0 ` `        ``if` `(product == 0) { ` `            ``product = 1; ` `            ``curr = ``""``; ` `        ``} ` `    ``} ` ` `  `    ``// Return the subString with maximum product ` `    ``return` `answer; ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main(String[] args) ` `{ ` `    ``String str = ``"sdtfakdhdahdzz"``; ` ` `  `    ``int` `n = str.Length; ` ` `  `    ``// Function call ` `    ``Console.Write(maximumProduct(str, n) +``"\n"``); ` ` `  `} ` `} ` `// This code is contributed by PrinciRaj1992 `

Output:

```hdzz
```

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