# Project Euler 051
# Smallest prime in an eight prime family by digit replacement.
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
struct DigitSlot {
dig: i32,
rep: i32
}
function pow10(n: i32) -> i64 {
let mut r: i64 = 1
let mut i: i32 = 0
while i < n {
r = r * 10
i = i + 1
}
return r
}
function main() -> i32 {
let limit: i64 = 1000000
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 slots: ptr<DigitSlot> = calloc(10, 8) as ptr<DigitSlot>
if slots == null { return 1 }
let mut ans: i64 = 0
let mut n: i64 = 10
while n < limit {
if sieve[n] == 0 {
let mut x: i64 = n
let mut nd: i32 = 0
while x > 0 {
slots[nd].dig = (x % 10) as i32
x = x / 10
nd = nd + 1
}
# slots[0].dig = LSD; slots[nd-1].dig = MSD
let masks: i32 = (1 << nd) - 1
let mut mask: i32 = 1
while mask <= masks {
# require replaced digits equal
let mut same: i32 = -1
let mut ok_mask: bool = true
let mut i: i32 = 0
while i < nd {
if (mask & (1 << i)) != 0 {
if same < 0 {
same = slots[i].dig
} elif slots[i].dig != same {
ok_mask = false
break
}
}
i = i + 1
}
if ok_mask {
let mut count: i32 = 0
let mut first: i64 = 0
let mut d: i32 = 0
while d <= 9 {
# build number with replaced digits = d
let mut v: i64 = 0
let mut place: i64 = 1
let mut lead_zero: bool = false
i = 0
while i < nd {
let mut digit: i32 = slots[i].dig
if (mask & (1 << i)) != 0 {
digit = d
}
if i == nd - 1 && digit == 0 {
lead_zero = true
}
v = v + (digit as i64) * place
place = place * 10
i = i + 1
}
if !lead_zero && v < limit && sieve[v] == 0 {
count = count + 1
if first == 0 {
first = v
}
}
d = d + 1
}
if count >= 8 {
if ans == 0 || first < ans {
ans = first
}
}
}
mask = mask + 1
}
if ans != 0 && n > ans {
break
}
}
n = n + 1
}
printf("%lld\n", ans)
free(slots)
free(sieve)
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; }
typedef struct DigitSlot DigitSlot;
struct DigitSlot {
int32_t dig;
int32_t rep;
};
int64_t pow10_i32(int32_t n);
int32_t main(void);
int64_t pow10_i32(int32_t n) {
int64_t r = 1;
int32_t i = 0;
while (i < n) {
r = (r * 10);
i = (i + 1);
}
return r;
}
int32_t main(void) {
int64_t limit = 1000000;
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);
}
DigitSlot* slots = (DigitSlot*)(((DigitSlot*)(calloc(10, 8))));
if (slots == NULL) {
return 1;
}
int64_t ans = 0;
int64_t n = 10;
while (n < limit) {
if (sieve[n] == 0) {
int64_t x = n;
int32_t nd = 0;
while (x > 0) {
slots[nd].dig = ((int32_t)(FLOW_CHECKED_MOD((x), (10))));
x = FLOW_CHECKED_DIV((x), (10));
nd = (nd + 1);
}
int32_t masks = (FLOW_CHECKED_SHL((1), (nd)) - 1);
int32_t mask = 1;
while (mask <= masks) {
int32_t same = (-1);
bool ok_mask = 1;
int32_t i = 0;
while (i < nd) {
if ((mask & FLOW_CHECKED_SHL((1), (i))) != 0) {
if (same < 0) {
same = slots[i].dig;
} else if (slots[i].dig != same) {
ok_mask = 0;
break;
}
}
i = (i + 1);
}
if (ok_mask) {
int32_t count = 0;
int64_t first = 0;
int32_t d = 0;
while (d <= 9) {
int64_t v = 0;
int64_t place = 1;
bool lead_zero = 0;
i = 0;
while (i < nd) {
int32_t digit = slots[i].dig;
if ((mask & FLOW_CHECKED_SHL((1), (i))) != 0) {
digit = d;
}
if ((i == (nd - 1) && digit == 0)) {
lead_zero = 1;
}
v = (v + (((int64_t)(digit)) * place));
place = (place * 10);
i = (i + 1);
}
if ((((!(lead_zero)) && v < limit) && sieve[v] == 0)) {
count = (count + 1);
if (first == 0) {
first = v;
}
}
d = (d + 1);
}
if (count >= 8) {
if ((ans == 0 || first < ans)) {
ans = first;
}
}
}
mask = (mask + 1);
}
if ((ans != 0 && n > ans)) {
break;
}
}
n = (n + 1);
}
printf("%lld\n", ans);
free(slots);
free(sieve);
return 0;
}