Leetcode 2278: Percentage of Letter in String

Input: You are given a string `s` and a character `letter` where `s` consists of lowercase English letters and `letter` is a lowercase English letter.

Example: Input: s = "hello", letter = "l"

Constraints:

• 1 <= s.length <= 100

• s consists of lowercase English letters.

• letter is a lowercase English letter.

Output: Return the percentage of characters in `s` that are equal to `letter`, rounded down to the nearest whole percent.

Example: Output: 40

Constraints:

Goal: Find the percentage of occurrences of `letter` in the string `s` and return it as an integer.

Steps:

• Count how many times `letter` appears in the string `s`.

• Calculate the percentage by dividing the count by the length of the string and multiplying by 100.

• Return the integer part of the percentage.

Goal: The solution must efficiently handle strings with lengths up to 100 characters.

Steps:

Assumptions:

• The string `s` is not empty.

• The character `letter` exists within the alphabet.

• Input: Input: s = "hello", letter = "l"

• Explanation: In this case, the letter 'l' appears 2 times out of 5 characters in the string 'hello'. The percentage is 2 / 5 * 100 = 40%, so the output is 40.

• Input: Input: s = "abcabc", letter = "a"

• Explanation: The letter 'a' appears 2 times out of 6 characters in the string 'abcabc'. The percentage is 2 / 6 * 100 = 33.33%. When rounded down, the result is 33.

Approach: To solve this problem, we will count how many times the letter appears in the string, calculate the percentage, and return the rounded down value.

Observations:

• The percentage is calculated by dividing the count of the letter by the length of the string and multiplying by 100.

• Rounding down is equivalent to using integer division in many programming languages.

• The problem is straightforward and involves basic counting and arithmetic operations.

Steps:

• Initialize a counter to track how many times the letter appears in the string.

• Use the count method or a loop to count the occurrences of `letter` in the string `s`.

• Calculate the percentage and round it down by performing integer division.

Empty Inputs:

• There are no empty inputs, as the length of the string is guaranteed to be at least 1.

Large Inputs:

• The solution should work for strings with a length of up to 100 characters.

Special Values:

• If the letter does not appear in the string, the percentage will be 0.

Constraints:

• The solution must handle up to 100 characters efficiently.

int percentageLetter(string s, char letter) {
    return 100 * count(begin(s), end(s), letter) / s.size();
}

1 : Function Declaration

int percentageLetter(string s, char letter) {

This is the function header for `percentageLetter`, which takes a string `s` and a character `letter` as inputs. The function returns an integer representing the percentage of times `letter` appears in the string `s`.

2 : Return Statement

    return 100 * count(begin(s), end(s), letter) / s.size();

The function uses the `count` function to determine how many times `letter` appears in the string `s`. It then multiplies this count by 100 and divides it by the total size of the string `s` to calculate the percentage of the letter's occurrences in the string.

Best Case: O(n)

Average Case: O(n)

Worst Case: O(n)

Description: The time complexity is O(n), where n is the length of the string `s`, because we need to iterate through the string to count the occurrences of `letter`.

Best Case: O(1)

Worst Case: O(1)

Description: The space complexity is O(1) because we are using only a few variables to store the result.

Leetcode 2278: Percentage of Letter in String

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