Program to find cost to remove consecutive duplicate characters with costs in C++?

Suppose we have a string with lowercase letters and we also have a list of non-negative values called costs, the string and the list have the same length. We can delete character s[i] for cost costs[i], and then both s[i] and costs[i] is removed. We have to find the minimum cost to delete all consecutively repeating characters.

So, if the input is like s = "xxyyx" nums = [2, 3, 10, 4, 6], then the output will be 6, as we can delete s[0] and s[3] for a total cost of 2 + 4 = 6.

To solve this, we will follow these steps

Define one stack st
cost := 0
for initialize i := 0, when i < size of s, update (increase i by 1), do:
- if size of st is not 0 and s[top of st] is same as s[i], then:
  - if nums[top of st] > nums[i], then:
    - cost := cost + nums[i]
  - otherwise:
    - cost := cost + nums[top of st]
    - pop element from st
    - push i into st
- otherwise
  - push i into st
return cost

Let us see the following implementation to get better understanding

Example

Live Demo

#include <bits/stdc++.h>
using namespace std;

class Solution {
   public:
   int solve(string s, vector<int>& nums) {
      stack<int> st;
      int cost = 0;
      for (int i = 0; i < s.size(); ++i) {
         if (st.size() && s[st.top()] == s[i]) {
            if (nums[st.top()] > nums[i]) {
               cost += nums[i];
            } else {
               cost += nums[st.top()];
               st.pop();
               st.push(i);
            }
         } else {
            st.push(i);
         }
      }
      return cost;
   }
};


int solve(string s, vector<int>& nums) {
   return (new Solution())->solve(s, nums);
}

main(){
   vector<int> v = {2, 3, 10, 4, 6};
   string s = "xxyyx";
   cout << solve(s, v);
}