# Project Euler 231
# Prime factor sum of C(20000000, 15000000).
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function add_fact(n: i64, primes: ptr<i64>, pc: i64) -> i64 {
let mut total: i64 = 0
let mut i: i64 = 0
while i < pc {
let p: i64 = primes[i]
if p > n { break }
let mut multiple: i64 = p
let mut count: i64 = n / multiple
while count > 0 {
total = total + p * count
if multiple > n / p { break }
multiple = multiple * p
count = n / multiple
}
i = i + 1
}
return total
}
function main() -> i32 {
let N: i64 = 20000000
let K: i64 = 15000000
let sieve: ptr<i8> = calloc(N + 1, 1)
let primes: ptr<i64> = calloc(N / 10, 8)
if sieve == null || primes == null { return 1 }
let mut i: i64 = 0
while i <= N {
sieve[i] = 1
i = i + 1
}
sieve[0] = 0
sieve[1] = 0
i = 2
while i * i <= N {
if sieve[i] == 1 {
let mut j: i64 = i * i
while j <= N {
sieve[j] = 0
j = j + i
}
}
i = i + 1
}
let mut pc: i64 = 0
i = 2
while i <= N {
if sieve[i] == 1 {
primes[pc] = i
pc = pc + 1
}
i = i + 1
}
let ans: i64 = add_fact(N, primes, pc) - add_fact(N - K, primes, pc) - add_fact(K, primes, pc)
printf("%lld\n", ans)
free(sieve); free(primes)
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 add_fact_i64_ptr_i64_i64(int64_t n, int64_t* primes, int64_t pc);
int32_t main(void);
int64_t add_fact_i64_ptr_i64_i64(int64_t n, int64_t* primes, int64_t pc) {
int64_t total = 0;
int64_t i = 0;
while (i < pc) {
int64_t p = primes[i];
if (p > n) {
break;
}
int64_t multiple = p;
int64_t count = FLOW_CHECKED_DIV((n), (multiple));
while (count > 0) {
total = (total + (p * count));
if (multiple > FLOW_CHECKED_DIV((n), (p))) {
break;
}
multiple = (multiple * p);
count = FLOW_CHECKED_DIV((n), (multiple));
}
i = (i + 1);
}
return total;
}
int32_t main(void) {
int64_t N = 20000000;
int64_t K = 15000000;
int8_t* sieve = (int8_t*)(calloc((N + 1), 1));
int64_t* primes = (int64_t*)(calloc(FLOW_CHECKED_DIV((N), (10)), 8));
if ((sieve == NULL || primes == NULL)) {
return 1;
}
int64_t i = 0;
while (i <= N) {
sieve[i] = 1;
i = (i + 1);
}
sieve[0] = 0;
sieve[1] = 0;
i = 2;
while ((i * i) <= N) {
if (sieve[i] == 1) {
int64_t j = (i * i);
while (j <= N) {
sieve[j] = 0;
j = (j + i);
}
}
i = (i + 1);
}
int64_t pc = 0;
i = 2;
while (i <= N) {
if (sieve[i] == 1) {
primes[pc] = i;
pc = (pc + 1);
}
i = (i + 1);
}
int64_t ans = ((add_fact_i64_ptr_i64_i64(N, primes, pc) - add_fact_i64_ptr_i64_i64((N - K), primes, pc)) - add_fact_i64_ptr_i64_i64(K, primes, pc));
printf("%lld\n", ans);
free(sieve);
free(primes);
return 0;
}