Reverse Degree of a String - Practice Coding Problems

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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Understanding the Visualization

Input String

String with lowercase letters

Calculate Products

For each char: reverse_alphabet_value × position

Sum Results

Add all products to get final degree

Key Takeaway

🎯 Key Insight: Use formula 27-(char-'a') to efficiently get reverse alphabet values

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

Approach	Time	Space	Notes
✓ Formula-Based Calculation	O(n)	O(1)	Use mathematical formula to directly compute reverse alphabet values without lookup
Direct Calculation	O(n)	O(1)	Iterate through string, calculate reverse alphabet value for each character, multiply by position, sum all

Formula-Based Calculation — Algorithm Steps

Use formula: 27 - (char - 'a') for reverse alphabet value
Multiply by (index + 1) for 1-indexed position
Accumulate sum in single pass

Visualization

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Step-by-Step Walkthrough

Apply Formula

Use 27 - (char - 'a') for each character

Multiply Position

Multiply by 1-indexed position

Accumulate

Sum all results in one pass

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++) {
        total += (27 - (s[i] - 'a')) * (i + 1);
    }
    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 pass through string, each character processed in O(1)

✓ Linear Growth

Space Complexity

O(1)

Only using constant extra variables

✓ 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

Visualization

Related Problems

Common Approaches

Formula-Based Calculation — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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