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| #include <stdio.h> | |
| uint64_t square(uint8_t index) { | |
| // the number of grains on a given square | |
| if (index < 1 || index > 64) { | |
| return 0; | |
| } | |
| return (uint64_t)1 << (index - 1); | |
| } |
fortune-c
/ sum_square_diff.c
Last active
April 14, 2026 19:29
Compute the difference between the square of the sum and the sum of the squares of the first N natural numbers using efficient mathematical formulas. A classic problem highlighting optimization and algorithmic thinking.
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| // Calculates (1 + 2 + ... + n)^2 | |
| unsigned int square_of_sum(unsigned int n) { | |
| unsigned int sum = (n * (n + 1)) / 2; | |
| return sum * sum; | |
| } | |
| // Calculates (1^2 + 2^2 + ... + n^2) | |
| unsigned int sum_of_squares(unsigned int n) { | |
| return (1LL * n * (n + 1) * (2 * n + 1)) / 6; | |
| } |
fortune-c
/ leap.c
Last active
April 14, 2026 16:23
A leap year (in the Gregorian calendar) occurs: In every year that is evenly divisible by 4. Unless the year is evenly divisible by 100, in which case it's only a leap year if the year is also evenly divisible by 400. Some examples: 1997 was not a leap year as it's not divisible by 4. 1900 was not a leap year as it's not divisible by 400. 2000 w…
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| bool leap_year(int year){ | |
| if(year % 400==0 || (year % 4 == 0 && year % 100! =0)) { | |
| printf("%d is a leap year\n", year); | |
| return true; | |
| } | |
| return 0; | |
| } |