1578. Minimum Deletion Cost to Avoid Repeating Letters.md

1578. Minimum Deletion Cost to Avoid Repeating Letters

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the third one in Weekly Contest 205.

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Difficulty : Medium

Related Topics : Greedy

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Given a string s and an array of integers cost where cost[i] is the cost of deleting the i^th character in s.

Return the minimum cost of deletions such that there are no two identical letters next to each other.

Notice that you will delete the chosen characters at the same time, in other words, after deleting a character, the costs of deleting other characters will not change.

Example 1:

Input: s = "abaac", cost = [1,2,3,4,5]
Output: 3
Explanation: Delete the letter "a" with cost 3 to get "abac" (String without two identical letters next to each other).

Example 2:

Input: s = "abc", cost = [1,2,3]
Output: 0
Explanation: You don't need to delete any character because there are no identical letters next to each other.

Example 3:

Input: s = "aabaa", cost = [1,2,3,4,1]
Output: 2
Explanation: Delete the first and the last character, getting the string ("aba").

Constraints:

• s.length == cost.length
• 1 <= s.length, cost.length <= 10^5
• 1 <= cost[i] <= 10^4
• s contains only lowercase English letters.

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Solution

• mine
  • Java
    • Runtime: 4 ms, faster than 100.00%, Memory Usage: 48.4 MB, less than 96.97% of Java online submissions

      // O(N)time
      // O(N)space
      public int minCost(String s, int[] cost) {
          char[] arr = s.toCharArray();
          int res = 0;
          int index = 0;
          for(int i = 1; i < arr.length; i++){
              if(arr[i] == arr[index]){
                  if(cost[index] > cost[i]){
                      res += cost[i];
                  }else{
                      res += cost[index];
                      index = i;
                  }
              }else{
                  index = i;
              }
          }
          return res;
      }
      

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