Minimum Number of Pushes to Type Word II

Problem Description

Ah, the age-old struggle of typing! You know, the one where you have to push buttons on your keyboard to form words? Welcome to the “Minimum Number of Pushes to Type Word II” problem on LeetCode, where we take this struggle to a whole new level. Imagine you’re trying to type a word, but your keyboard is a bit… quirky. Each letter requires a certain number of pushes, and you want to minimize that effort.

Picture this: You’re at a party, and someone asks you to type “supercalifragilisticexpialidocious” on a keyboard that only has 8 buttons. You’d probably need a personal trainer for your fingers after that! The goal here is to find out how many pushes you need to type a given word, based on the frequency of each letter.

Code Solution


class Solution {
    public int minimumPushes(String word) {
        int ans = 0;
        int[] count = new int[26];

        for (final char c : word.toCharArray())
            ++count[c - 'a'];

        Arrays.sort(count);

        for (int i = 0; i < 26; ++i)
            ans += count[26 - i - 1] * (i / 8 + 1);

        return ans;
    }
}

Approach

The approach here is as straightforward as it gets. We count the occurrences of each letter in the word, sort these counts, and then calculate the total pushes required based on how many letters can be typed with each push. The logic is simple: the more frequent a letter is, the fewer pushes it should take to type it.

Time and Space Complexity

Complexity Type	Complexity
Time Complexity	O(n + k log k), where n is the length of the word and k is the number of unique letters (at most 26).
Space Complexity	O(1), since we are using a fixed-size array of size 26 to store letter counts.

Real-World Example

Imagine you're a barista at a coffee shop, and customers keep ordering complicated drinks with names like "Caramel Macchiato" or "Venti Iced Caramel Cloud Macchiato." Each time you type these names into the register, you want to minimize the number of keystrokes. By knowing which letters are used most frequently in your customers' orders, you can optimize your typing strategy and save your fingers from cramping up!