# Project Euler 214
# Sum of primes < 40e6 with totient chain length 25.
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function main() -> i32 {
let LIMIT: i64 = 40000000
let MAX_STEPS: i32 = 25
let tot: ptr<i32> = calloc(LIMIT, 4)
let chain: ptr<i16> = calloc(LIMIT, 2)
if tot == null || chain == null { return 1 }
let mut i: i64 = 0
while i < LIMIT {
tot[i] = i as i32
i = i + 1
}
i = 2
while i < LIMIT {
if tot[i] == i as i32 {
let mut j: i64 = i
while j < LIMIT {
tot[j] = tot[j] - tot[j] / (i as i32)
j = j + i
}
}
i = i + 1
}
chain[1] = 1
i = 2
while i < LIMIT {
chain[i] = (chain[tot[i] as i64] as i32 + 1) as i16
i = i + 1
}
let mut result: i64 = 0
i = 2
while i < LIMIT {
if tot[i] == i as i32 - 1 {
# prime: totient(p)=p-1
if chain[i] as i32 == MAX_STEPS {
result = result + i
}
}
i = i + 1
}
# Wait: for prime p, tot[p] should be p-1 after sieve. Check: initially tot[p]=p, then tot[p]=p-p/p=p-1. Yes.
# But condition tot[i]==i-1 identifies primes. Good.
printf("%lld\n", result)
free(tot); free(chain)
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; }
int32_t main(void);
int32_t main(void) {
int64_t LIMIT = 40000000;
int32_t MAX_STEPS = 25;
int32_t* tot = (int32_t*)(calloc(LIMIT, 4));
int16_t* chain = (int16_t*)(calloc(LIMIT, 2));
if ((tot == NULL || chain == NULL)) {
return 1;
}
int64_t i = 0;
while (i < LIMIT) {
tot[i] = ((int32_t)(i));
i = (i + 1);
}
i = 2;
while (i < LIMIT) {
if (tot[i] == ((int32_t)(i))) {
int64_t j = i;
while (j < LIMIT) {
tot[j] = (tot[j] - FLOW_CHECKED_DIV((tot[j]), (((int32_t)(i)))));
j = (j + i);
}
}
i = (i + 1);
}
chain[1] = 1;
i = 2;
while (i < LIMIT) {
chain[i] = ((int16_t)((((int32_t)(chain[((int64_t)(tot[i]))])) + 1)));
i = (i + 1);
}
int64_t result = 0;
i = 2;
while (i < LIMIT) {
if (tot[i] == (((int32_t)(i)) - 1)) {
if (((int32_t)(chain[i])) == MAX_STEPS) {
result = (result + i);
}
}
i = (i + 1);
}
printf("%lld\n", result);
free(tot);
free(chain);
return 0;
}