Given 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 = “neveropen”
Output: neveropen
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 <bits/stdc++.h>using namespace std;// Function to return the value of a characterint value(char x){ return (int)(x - 'a');}// Function to find the maximum product substringstring 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 codeint 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 subStringclass GFG{ // Function to return the value of a characterstatic int value(char x){ return (int)(x - 'a');} // Function to find the maximum product subStringstatic 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 codepublic 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 characterdef value(x): return (ord(x) - ord('a'))# Function to find the maximum product subdef 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 codeif __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 subStringusing System;public class GFG{// Function to return the value of a characterstatic int value(char x){ return (int)(x - 'a');}// Function to find the maximum product subStringstatic 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 codepublic 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 |
Javascript
<script>// Javascript program to find the// maximum product subString// Function to return the value of a characterfunction value(x){ return (x.charCodeAt() - 'a'.charCodeAt());} // Function to find the maximum product subStringfunction maximumProduct(str, n){ // To store subStrings let answer = "", curr = ""; let maxProduct = 0, product = 1; for (let i = 0; i < n; i++) { product *= (1 * 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 let str = "sdtfakdhdahdzz"; let n = str.length; // Function call document.write(maximumProduct(str, n) +"<br/>"); </script> |
Output:
hdzz
Time Complexity: O(N)
Auxiliary Space: O(1)
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