Reverse Degree of a String

Reverse Degree of a String - Problem

String Simulation Easy

Given a string s, calculate its reverse degree.

The reverse degree is calculated as follows:

For each character, multiply its position in the reversed alphabet ('a' = 26, 'b' = 25, ..., 'z' = 1) with its position in the string (1-indexed).
Sum these products for all characters in the string.

Return the reverse degree of s.

Input & Output

Example 1 — Basic Case

$ Input: s = "abc"

› Output: 148

💡 Note: a=26×1=26, b=25×2=50, c=24×3=72. Total: 26+50+72=148

Example 2 — Single Character

$ Input: s = "z"

› Output: 1

💡 Note: z has reverse value 1, position 1: 1×1=1

Example 3 — Repeated Characters

$ Input: s = "aa"

› Output: 78

💡 Note: First a: 26×1=26, second a: 26×2=52. Total: 26+52=78

Constraints

1 ≤ s.length ≤ 1000
s consists of lowercase English letters only

Visualization

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Asked in

G Google 15 M Microsoft 12

The key insight is to use the formula 27 - (char - 'a') to get reverse alphabet values efficiently. Best approach processes each character once, multiplying reverse value by 1-indexed position. Time: O(n), Space: O(1)

Common Approaches

✓ Direct Calculation

⏱️ Time: O(n) Space: O(1)

For each character in the string, we calculate its reverse alphabet position (where 'a'=26, 'b'=25, etc.), multiply by the character's 1-indexed position in the string, and add to running sum.

Formula-Based Calculation

⏱️ Time: O(n) Space: O(1)

Instead of using lookup tables or multiple calculations, we use the direct formula: reverse_value = 27 - (char - 'a'). This eliminates any overhead and makes the calculation as efficient as possible.

Direct Calculation — Algorithm Steps

Iterate through each character with its position
Calculate reverse alphabet value: 27 - (char - 'a')
Multiply by 1-indexed position
Add to total sum

Visualization

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Step-by-Step Walkthrough

Parse Characters

Go through each character with its position

Calculate Values

Get reverse alphabet value and multiply by position

Sum Results

Add all products together

Code -

solution.c — C

#include <stdio.h>
#include <string.h>

int solution(char* s) {
    int total = 0;
    int len = strlen(s);
    for (int i = 0; i < len; i++) {
        char c = s[i];
        int reverseValue = 27 - (c - 'a');
        int position = i + 1;
        total += reverseValue * position;
    }
    return total;
}

int main() {
    char s[1000];
    fgets(s, sizeof(s), stdin);
    s[strcspn(s, "\n")] = 0;
    int result = solution(s);
    printf("%d\n", result);
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(n)

Single loop through the string of length n

✓ Linear Growth

Space Complexity

O(1)

Only using a few variables for calculation

✓ Linear Space

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Medium Frequency

~8 min Avg. Time

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Ln 1, Col 1

Smart Actions

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Input & Output

Constraints

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Related Problems

Common Approaches

Direct Calculation — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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