#include <stdio.h>
/*
sort_three(a, b, c)
-------------------
Sorts three integers in ascending order using the simplest correct method.
Why this algorithm?
• Sorting exactly three numbers can be done with only three comparisons.
• Each comparison conditionally swaps two values.
• No loops, no arrays, no dynamic memory — extremely lightweight.
• Idiomatic C: uses a tiny helper swap function for clarity.
Algorithm:
1. Ensure a <= c
2. Ensure a <= b
3. Ensure b <= c
After these three steps, the values are guaranteed to be sorted.
*/
void swap(int *x, int *y) {
int temp = *x;
*x = *y;
*y = temp;
}
void sort_three(int *a, int *b, int *c) {
if (*a > *c)
swap(a, c);
if (*a > *b)
swap(a, b);
if (*b > *c)
swap(b, c);
}
int main(void) {
int values[][3] = {
{3, 1, 2},
{10, 5, 7},
{100, 50, 75},
{9, 9, 1},
{42, 0, -5},
{8, 4, 4}
};
int count = sizeof(values) / sizeof(values[0]);
for (int i = 0; i < count; i++) {
int a = values[i][0];
int b = values[i][1];
int c = values[i][2];
sort_three(&a, &b, &c);
printf("sorted(%d, %d, %d) = %d, %d, %d\n",
values[i][0], values[i][1], values[i][2],
a, b, c);
}
return 0;
}
/*
run:
sorted(3, 1, 2) = 1, 2, 3
sorted(10, 5, 7) = 5, 7, 10
sorted(100, 50, 75) = 50, 75, 100
sorted(9, 9, 1) = 1, 9, 9
sorted(42, 0, -5) = -5, 0, 42
sorted(8, 4, 4) = 4, 4, 8
*/
