Is Total Distance to Type a String Using One Finger easy or hard?

The problem is typically classified as Medium because it requires recognizing the preprocessing optimization. The brute approach works but repeatedly scans the keyboard. Efficient solutions use a hash map or array to reduce lookups to O(1) and achieve an overall O(n) runtime.

Total Distance to Type a String Using One Finger Python/Java solution

The standard implementation first builds a dictionary (Python) or HashMap/array (Java) mapping each keyboard character to its position. Then iterate through the word, compute absolute differences between consecutive positions, and sum them. This approach runs in O(n) time and uses O(1) additional space.

How to solve Total Distance to Type a String Using One Finger in O(n)?

First build a map or array that stores the index of every character in the keyboard layout. Then iterate through the word and compute the distance between the current character and the previous one using abs(position[a] - position[b]). Accumulate these values to get the total distance. Because each lookup is O(1), the overall complexity is O(n).

What is the best approach for Total Distance to Type a String Using One Finger?

The best approach builds a mapping from each keyboard character to its index, then simulates typing the word. This allows constant‑time lookup of positions and computes the distance between consecutive characters using absolute difference. The total runtime is O(n) where n is the word length, with O(26) extra space for the mapping.

Is Total Distance to Type a String Using One Finger asked at Google/Amazon/Meta?

Problems involving keyboard layouts, string indexing, and distance simulation commonly appear in interviews at companies like Google, Amazon, and Meta. While this exact question may vary, the pattern of preprocessing indices and computing movement cost is frequently tested in string and simulation questions.

What data structure is used in Total Distance to Type a String Using One Finger?

The main data structure is a hash table or a fixed array used to store the keyboard index of each character. This enables constant‑time access when calculating distances between characters. The rest of the solution is a straightforward simulation over the input string.

What is the time complexity of Total Distance to Type a String Using One Finger?

The optimal solution runs in O(n) time where n is the length of the word. A preprocessing step maps each character in the keyboard to its index in O(26) time. Each character in the word is then processed once with constant‑time lookups, so the total runtime remains linear.

Description Hints 4 Solution Video 5:12

3846. Total Distance to Type a String Using One Finger

Medium89.9% acceptancePremium elsewhere, free here

There is a special keyboard where keys are arranged in a rectangular grid as follows.

q	w	e	r	t	y	u	i	o	p
a	s	d	f	g	h	j	k	l
z	x	c	v	b	n	m

You are given a string s that consists of lowercase English letters only. Return an integer denoting the total distance to type s using only one finger. Your finger starts on the key 'a'.

The distance between two keys at (r1, c1) and (r2, c2) is |r1 - r2| + |c1 - c2|.

Example 1:

Input: s = "hello"

Output: 17

Explanation:

Your finger starts at 'a', which is at (1, 0).
Move to 'h', which is at (1, 5). The distance is |1 - 1| + |0 - 5| = 5.
Move to 'e', which is at (0, 2). The distance is |1 - 0| + |5 - 2| = 4.
Move to 'l', which is at (1, 8). The distance is |0 - 1| + |2 - 8| = 7.
Move to 'l', which is at (1, 8). The distance is |1 - 1| + |8 - 8| = 0.
Move to 'o', which is at (0, 8). The distance is |1 - 0| + |8 - 8| = 1.
Total distance is 5 + 4 + 7 + 0 + 1 = 17.

Example 2:

Input: s = "a"

Output: 0

Explanation:

Your finger starts at 'a', which is at (1, 0).
Move to 'a', which is at (1, 0). The distance is |1 - 1| + |0 - 0| = 0.
Total distance is 0.

Constraints:

1 <= s.length <= 10⁴
s consists of lowercase English letters only.

Topics

Hash Table String

Hints open one at a time

Hint 1

Map each character to its (row, col) position on the keyboard grid.

Hint 2

Start from the position of 'a' and process the string from left to right.

Hint 3

For each move, add the Manhattan distance abs(r1 - r2) + abs(c1 - c2) between consecutive keys.

Hint 4

Accumulate the total distance and return the sum.

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3846. Total Distance to Type a String Using One Finger

Topics

Hints open one at a time

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