# Project Euler 049
# Concatenate the three terms of the 4-digit prime permutation arithmetic
# sequence (excluding 1487/4817/8147).
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function digit_sig(n0: i64) -> i64 {
let mut counts: array<i32, 10> = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
let mut n: i64 = n0
while n > 0 {
let d: i32 = (n % 10) as i32
counts[d] = counts[d] + 1
n = n / 10
}
let mut sig: i64 = 0
let mut d: i32 = 0
while d < 10 {
sig = sig * 10 + (counts[d] as i64)
d = d + 1
}
return sig
}
function main() -> i32 {
let limit: i64 = 10000
let sieve: ptr<i8> = calloc(limit, 1)
if sieve == null { return 1 }
sieve[0] = 1
sieve[1] = 1
let mut p: i64 = 2
while p * p < limit {
if sieve[p] == 0 {
let mut m: i64 = p * p
while m < limit {
sieve[m] = 1
m = m + p
}
}
p = p + 1
}
let mut a: i64 = 1000
while a < 10000 {
if sieve[a] == 0 {
let sig_a: i64 = digit_sig(a)
let mut b: i64 = a + 1
while b < 10000 {
if sieve[b] == 0 && digit_sig(b) == sig_a {
let c: i64 = b + (b - a)
if c < 10000 && sieve[c] == 0 && digit_sig(c) == sig_a {
if a != 1487 {
let ans: i64 = a * 100000000 + b * 10000 + c
printf("%lld\n", ans)
free(sieve)
return 0
}
}
}
b = b + 1
}
}
a = a + 1
}
free(sieve)
return 1
}
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 digit_sig_i64(int64_t n0);
int32_t main(void);
int64_t digit_sig_i64(int64_t n0) {
int32_t counts[10] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
int64_t n = n0;
while (n > 0) {
int32_t d = ((int32_t)(FLOW_CHECKED_MOD((n), (10))));
counts[d] = ((((unsigned)(d) < 10) ? counts[d] : (fprintf(stderr, "array index %d out of bounds (size %d)\n", (int)(d), 10), flow_fault_handler("array index out of bounds"), counts[0])) + 1);
n = FLOW_CHECKED_DIV((n), (10));
}
int64_t sig = 0;
int32_t d = 0;
while (d < 10) {
sig = ((sig * 10) + ((int64_t)((((unsigned)(d) < 10) ? counts[d] : (fprintf(stderr, "array index %d out of bounds (size %d)\n", (int)(d), 10), flow_fault_handler("array index out of bounds"), counts[0])))));
d = (d + 1);
}
return sig;
}
int32_t main(void) {
int64_t limit = 10000;
int8_t* sieve = (int8_t*)(calloc(limit, 1));
if (sieve == NULL) {
return 1;
}
sieve[0] = 1;
sieve[1] = 1;
int64_t p = 2;
while ((p * p) < limit) {
if (sieve[p] == 0) {
int64_t m = (p * p);
while (m < limit) {
sieve[m] = 1;
m = (m + p);
}
}
p = (p + 1);
}
int64_t a = 1000;
while (a < 10000) {
if (sieve[a] == 0) {
int64_t sig_a = digit_sig_i64(a);
int64_t b = (a + 1);
while (b < 10000) {
if ((sieve[b] == 0 && digit_sig_i64(b) == sig_a)) {
int64_t c = (b + (b - a));
if (((c < 10000 && sieve[c] == 0) && digit_sig_i64(c) == sig_a)) {
if (a != 1487) {
int64_t ans = (((a * 100000000) + (b * 10000)) + c);
printf("%lld\n", ans);
free(sieve);
return 0;
}
}
}
b = (b + 1);
}
}
a = (a + 1);
}
free(sieve);
return 1;
}