Given string str of lowercase alphabets and an array cost[], where cost[i] represents the cost of deletion of ith character in the given string. The task is to find the maximum possible cost to obtain a string having no adjacent pair of same characters, by deleting the same pair of consecutive characters.
Examples:
Input: str = “abaac”, cost = {1, 2, 3, 4, 5}
Output: 4
Explanation:
Remove character ‘a’ from position 4 in one based indexingInput: str = “abc”, cost = {1, 2, 3}
Output: 0
Explanation:
No consecutive characters are found.
Naive Approach: The simplest approach is to traverse the given string to check for each character from a to z if there are substrings having only that character. Follow the steps below to solve the problem:
- Traverse from a to z to check substrings having only that character.
- If any substring is found, calculate the sum for removal of each character and subtract the minimum cost from it.
- Add the above sum in the total count.
- Repeat the above steps for every substring.
- Print the total count.
Time Complexity: O(N*26), where N is the length of the given string
Auxiliary Space: O(N)
Efficient Approach: Follow the below steps to optimize the above approach:
- Traverse the given string over the range of indices [0, N – 2] and initialize a variable, say maxCost, to store the maximum possible cost.
- Check if characters S[i] and S[i+1] are equal.
- If adjacent characters are equal, then add the maximum cost from cost[i] and cost[i + 1] to maxCost and shift the minimum cost to right by setting cost[i + 1] = min(cost[i], cost[i + 1]).
- After traversing the given string, print the value of maxCost.
Below is the implementation of the above approach:
C++
// C++ program for the above approach#include <bits/stdc++.h>using namespace std; // Function to find maximum cost to// remove consecutive charactersint Maxcost(string s, int cost[]){ // Initialize the count int count = 0; // Maximum cost int maxcost = 0, i = 0; // Traverse from 0 to len(s) - 2 while (i < s.size() - 1) { // If characters are identical if (s[i] == s[i + 1]) { // Add cost[i] if its maximum if (cost[i] > cost[i + 1]) maxcost += cost[i]; // Add cost[i + 1] // if its maximum else { maxcost += cost[i + 1]; cost[i + 1] = cost[i]; } } // Increment i i += 1; } // Return the final max count return maxcost;} // Driver Codeint main(){ // Given string s string s = "abaac"; // Given cost of removal int cost[] = {1, 2, 3, 4, 5}; // Function Call cout << Maxcost(s, cost); return 0;}// This is code contributed by gauravrajput1 |
Java
// Java program for the above approachimport java.io.*;import java.util.*; class GFG{ // Function to find maximum cost to // remove consecutive characters static int Maxcost(String s, int []cost){ // Maximum cost int maxcost = 0; int i = 0; // Traverse from 0 to len(s) - 2 while (i < s.length() - 1) { // If characters are identical if (s.charAt(i) == s.charAt(i + 1)) { // Add cost[i] if its maximum if (cost[i] > cost[i + 1]) maxcost += cost[i]; // Add cost[i + 1] // if its maximum else { maxcost += cost[i + 1]; cost[i + 1] = cost[i]; } } // Increment i i++; } // Return the final max count return maxcost;} // Driver codepublic static void main (String[] args){ // Given string s String s = "abaac"; // Given cost of removal int []cost = { 1, 2, 3, 4, 5 }; // Function call System.out.print(Maxcost(s, cost));}} // This code is contributed by code_hunt |
Python3
# Python3 program for the above approach # Function to find maximum cost to# remove consecutive charactersdef Maxcost(s, cost): # Initialize the count count = 0 # Maximum cost maxcost = 0 i = 0 # Traverse from 0 to len(s) - 2 while i < len(s) - 1: # If characters are identical if s[i] == s[i + 1]: # Add cost[i] if its maximum if cost[i] > cost[i + 1]: maxcost += cost[i] # Add cost[i + 1] if its # maximum else: maxcost += cost[i + 1] cost[i + 1] = cost[i] # Increment i i += 1 # Return the final max count return maxcost # Driver Code # Given string ss = "abaac" # Given cost of removalcost = [1, 2, 3, 4, 5] # Function Callprint(Maxcost(s, cost)) |
C#
// C# program for the above approachusing System; using System.Collections.Generic; class GFG{ // Function to find maximum cost to // remove consecutive characters static int Maxcost(string s, int []cost){ // Maximum cost int maxcost = 0; int i = 0; // Traverse from 0 to len(s) - 2 while (i < s.Length - 1) { // If characters are identical if (s[i] == s[i + 1]) { // Add cost[i] if its maximum if (cost[i] > cost[i + 1]) maxcost += cost[i]; // Add cost[i + 1] // if its maximum else { maxcost += cost[i + 1]; cost[i + 1] = cost[i]; } } // Increment i i++; } // Return the final max count return maxcost;} // Driver codepublic static void Main (string[] args){ // Given string s string s = "abaac"; // Given cost of removal int []cost = {1, 2, 3, 4, 5}; // Function call Console.Write(Maxcost(s, cost));}} // This code is contributed by rutvik_56 |
4
Time Complexity: O(N)
Auxiliary Space: O(N)
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