# Project Euler 309
# Integer crossing ladders with x,y < 10^6.
import euler.nt { gcd }
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function main() -> i32 {
let limit: i64 = 1000000
let counts: ptr<i32> = calloc(limit, 4)
if counts == null { return 1 }
let mut m: i64 = 2
while m * m < limit {
let mut n: i64 = (m & 1) + 1
while n < m {
if gcd(m, n) == 1 {
let a: i64 = m * m - n * n
let b: i64 = 2 * m * n
let c: i64 = m * m + n * n
let mut k: i64 = 1
while k * c < limit {
counts[k * a] = counts[k * a] + 1
counts[k * b] = counts[k * b] + 1
k = k + 1
}
}
n = n + 2
}
m = m + 1
}
let offs: ptr<i64> = calloc(limit + 1, 8)
let mut total: i64 = 0
let mut h: i64 = 0
while h < limit {
offs[h] = total
total = total + (counts[h] as i64)
h = h + 1
}
offs[limit] = total
let partners: ptr<i32> = calloc(total, 4)
let fill: ptr<i32> = calloc(limit, 4)
if partners == null || fill == null { return 1 }
m = 2
while m * m < limit {
let mut n: i64 = (m & 1) + 1
while n < m {
if gcd(m, n) == 1 {
let a: i64 = m * m - n * n
let b: i64 = 2 * m * n
let c: i64 = m * m + n * n
let mut k: i64 = 1
while k * c < limit {
let aa: i64 = k * a
let bb: i64 = k * b
partners[offs[aa] + (fill[aa] as i64)] = bb as i32
fill[aa] = fill[aa] + 1
partners[offs[bb] + (fill[bb] as i64)] = aa as i32
fill[bb] = fill[bb] + 1
k = k + 1
}
}
n = n + 2
}
m = m + 1
}
let mut count: i64 = 0
h = 1
while h < limit {
let start: i64 = offs[h]
let end: i64 = offs[h + 1]
let mut left: i64 = start
while left < end {
let mut right: i64 = left + 1
while right < end {
let x: i64 = partners[left] as i64
let y: i64 = partners[right] as i64
if (x * y) % (x + y) == 0 {
count = count + 1
}
right = right + 1
}
left = left + 1
}
h = h + 1
}
printf("%lld\n", count)
free(counts); free(offs); free(partners); free(fill)
return 0
}
Generated C
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Flow runtime helpers */
typedef struct flow_temp_node { struct flow_temp_node* next; } flow_temp_node;
static flow_temp_node* flow_temp_head = NULL;
static int flow_temp_atexit_set = 0;
__attribute__((unused)) static void flow_temp_free_all(void) {
while (flow_temp_head) {
flow_temp_node* n = flow_temp_head;
flow_temp_head = n->next;
free(n);
}
}
__attribute__((unused)) static void* flow_temp_alloc(size_t nbytes) {
flow_temp_node* node = (flow_temp_node*)malloc(sizeof(flow_temp_node) + nbytes);
if (!node) return NULL;
node->next = flow_temp_head;
flow_temp_head = node;
if (!flow_temp_atexit_set) {
flow_temp_atexit_set = 1;
atexit(flow_temp_free_all);
}
return (void*)(node + 1);
}
#ifndef FLOW_DIAG
#define FLOW_DIAG(msg) fprintf(stderr, "%s", (msg))
#endif
#ifndef FLOW_LOG
#define FLOW_LOG(fmt, ...) printf(fmt, __VA_ARGS__)
#endif
#ifndef FLOW_LOG_EMPTY
#define FLOW_LOG_EMPTY(fmt) printf(fmt)
#endif
static char* flow_strcat(const char* a, const char* b) {
size_t la = strlen(a ? a : ""), lb = strlen(b ? b : "");
char* r = (char*)flow_temp_alloc(la + lb + 1);
if (!r) return NULL;
if (la) memcpy(r, a, la);
if (lb) memcpy(r + la, b, lb);
r[la + lb] = '\0';
return r;
}
#define __flow_in_arr(arr, val) __extension__ ({ \
int _found = 0; \
size_t _n = sizeof(arr)/sizeof((arr)[0]); \
for (size_t _i = 0; _i < _n; _i++) { \
if ((arr)[_i] == (val)) { _found = 1; break; } \
} _found; })
/* Unified fault handler (MISRA #279) — override with -DFLOW_FAULT_HANDLER=fn */
#ifndef FLOW_FAULT_HANDLER
__attribute__((unused)) static inline void flow_fault_handler(const char* msg) {
fprintf(stderr, "flow: %s\n", msg ? msg : "fault");
abort();
#if defined(__GNUC__) || defined(__clang__)
__builtin_unreachable();
#endif
}
#else
#define flow_fault_handler FLOW_FAULT_HANDLER
#endif
#define flow_div_by_zero_handler() flow_fault_handler("division by zero")
#define flow_shift_ub_handler() flow_fault_handler("invalid shift (amount out of range or left-shift of negative)")
#ifndef FLOW_CHECKED_DIV
#define FLOW_CHECKED_DIV(L, R) (((R) != 0) ? ((L) / (R)) : (flow_div_by_zero_handler(), (L) * 0))
#endif
#ifndef FLOW_CHECKED_MOD
#define FLOW_CHECKED_MOD(L, R) (((R) != 0) ? ((L) % (R)) : (flow_div_by_zero_handler(), (L) * 0))
#endif
#ifndef FLOW_CHECKED_SHL
#define FLOW_CHECKED_SHL(L, R) ((((R) >= 0) && ((unsigned long long)(R) < (sizeof(L) * 8ull)) && ((L) >= 0)) ? ((L) << (R)) : (flow_shift_ub_handler(), (L) * 0))
#endif
#ifndef FLOW_CHECKED_SHR
#define FLOW_CHECKED_SHR(L, R) ((((R) >= 0) && ((unsigned long long)(R) < (sizeof(L) * 8ull))) ? ((L) >> (R)) : (flow_shift_ub_handler(), (L) * 0))
#endif
#include <math.h>
void* _ui_state = NULL;
static inline float i32_to_f32(int32_t v) { return (float)v; }
/* Host stub for @gpu kernels (device codegen replaces this). */
static inline int32_t gpu_thread_id(void) { return 0; }
int64_t gcd_i64_i64(int64_t a0, int64_t b0);
int64_t lcm_i64_i64(int64_t a, int64_t b);
int64_t isqrt_i64(int64_t n);
int64_t mulmod_i64_i64_i64(int64_t a0, int64_t b0, int64_t mod);
int64_t mod_pow_i64_i64_i64(int64_t base, int64_t exp, int64_t mod);
bool is_prime_i64(int64_t n);
int32_t main(void);
int64_t gcd_i64_i64(int64_t a0, int64_t b0) {
int64_t a = a0;
int64_t b = b0;
while (b != 0) {
int64_t t = FLOW_CHECKED_MOD((a), (b));
a = b;
b = t;
}
return a;
}
int64_t lcm_i64_i64(int64_t a, int64_t b) {
if ((a == 0 || b == 0)) {
return 0;
}
return (FLOW_CHECKED_DIV((a), (gcd_i64_i64(a, b))) * b);
}
int64_t isqrt_i64(int64_t n) {
if (n < 2) {
return n;
}
int64_t x = n;
int64_t y = FLOW_CHECKED_DIV(((x + 1)), (2));
while (y < x) {
x = y;
y = FLOW_CHECKED_DIV(((x + FLOW_CHECKED_DIV((n), (x)))), (2));
}
return x;
}
int64_t mulmod_i64_i64_i64(int64_t a0, int64_t b0, int64_t mod) {
int64_t a = FLOW_CHECKED_MOD((a0), (mod));
int64_t b = FLOW_CHECKED_MOD((b0), (mod));
int64_t result = 0;
while (b > 0) {
if (FLOW_CHECKED_MOD((b), (2)) == 1) {
result = FLOW_CHECKED_MOD(((result + a)), (mod));
}
a = FLOW_CHECKED_MOD(((a * 2)), (mod));
b = FLOW_CHECKED_DIV((b), (2));
}
return result;
}
int64_t mod_pow_i64_i64_i64(int64_t base, int64_t exp, int64_t mod) {
if (mod == 1) {
return 0;
}
int64_t result = 1;
int64_t b = FLOW_CHECKED_MOD((base), (mod));
int64_t e = exp;
while (e > 0) {
if (FLOW_CHECKED_MOD((e), (2)) == 1) {
result = mulmod_i64_i64_i64(result, b, mod);
}
b = mulmod_i64_i64_i64(b, b, mod);
e = FLOW_CHECKED_DIV((e), (2));
}
return result;
}
bool is_prime_i64(int64_t n) {
if (n < 2) {
return 0;
}
if (n < 4) {
return 1;
}
if ((FLOW_CHECKED_MOD((n), (2)) == 0 || FLOW_CHECKED_MOD((n), (3)) == 0)) {
return 0;
}
int64_t i = 5;
while ((i * i) <= n) {
if ((FLOW_CHECKED_MOD((n), (i)) == 0 || FLOW_CHECKED_MOD((n), ((i + 2))) == 0)) {
return 0;
}
i = (i + 6);
}
return 1;
}
int32_t main(void) {
int64_t limit = 1000000;
int32_t* counts = (int32_t*)(calloc(limit, 4));
if (counts == NULL) {
return 1;
}
int64_t m = 2;
while ((m * m) < limit) {
int64_t n = ((m & 1) + 1);
while (n < m) {
if (gcd_i64_i64(m, n) == 1) {
int64_t a = ((m * m) - (n * n));
int64_t b = ((2 * m) * n);
int64_t c = ((m * m) + (n * n));
int64_t k = 1;
while ((k * c) < limit) {
counts[(k * a)] = (counts[(k * a)] + 1);
counts[(k * b)] = (counts[(k * b)] + 1);
k = (k + 1);
}
}
n = (n + 2);
}
m = (m + 1);
}
int64_t* offs = (int64_t*)(calloc((limit + 1), 8));
int64_t total = 0;
int64_t h = 0;
while (h < limit) {
offs[h] = total;
total = (total + ((int64_t)(counts[h])));
h = (h + 1);
}
offs[limit] = total;
int32_t* partners = (int32_t*)(calloc(total, 4));
int32_t* fill = (int32_t*)(calloc(limit, 4));
if ((partners == NULL || fill == NULL)) {
return 1;
}
m = 2;
while ((m * m) < limit) {
int64_t n = ((m & 1) + 1);
while (n < m) {
if (gcd_i64_i64(m, n) == 1) {
int64_t a = ((m * m) - (n * n));
int64_t b = ((2 * m) * n);
int64_t c = ((m * m) + (n * n));
int64_t k = 1;
while ((k * c) < limit) {
int64_t aa = (k * a);
int64_t bb = (k * b);
partners[(offs[aa] + ((int64_t)(fill[aa])))] = ((int32_t)(bb));
fill[aa] = (fill[aa] + 1);
partners[(offs[bb] + ((int64_t)(fill[bb])))] = ((int32_t)(aa));
fill[bb] = (fill[bb] + 1);
k = (k + 1);
}
}
n = (n + 2);
}
m = (m + 1);
}
int64_t count = 0;
h = 1;
while (h < limit) {
int64_t start = offs[h];
int64_t end = offs[(h + 1)];
int64_t left = start;
while (left < end) {
int64_t right = (left + 1);
while (right < end) {
int64_t x = ((int64_t)(partners[left]));
int64_t y = ((int64_t)(partners[right]));
if (FLOW_CHECKED_MOD(((x * y)), ((x + y))) == 0) {
count = (count + 1);
}
right = (right + 1);
}
left = (left + 1);
}
h = (h + 1);
}
printf("%lld\n", count);
free(counts);
free(offs);
free(partners);
free(fill);
return 0;
}