# Project Euler 250
# Subsets of {1^1..250250^250250} with sum divisible by 250; last 16 digits.
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function modpow(base: i64, exp: i64, mod: i64) -> i64 {
let mut r: i64 = 1
let mut b: i64 = base % mod
let mut e: i64 = exp
while e > 0 {
if e % 2 == 1 { r = (r * b) % mod }
b = (b * b) % mod
e = e / 2
}
return r
}
function main() -> i32 {
let LIMIT: i64 = 250250
let MOD: i64 = 10000000000000000
let arr: ptr<i64> = calloc(250, 8)
let nxt: ptr<i64> = calloc(250, 8)
if arr == null || nxt == null { return 1 }
arr[0] = 1
let mut i: i64 = 1
while i <= LIMIT {
let x: i64 = modpow(i, i, 250)
let mut y: i64 = 0
while y < 250 {
nxt[y] = 0
y = y + 1
}
y = 0
while y < 250 {
let a: i64 = arr[y]
if a != 0 {
nxt[y] = (nxt[y] + a) % MOD
let z: i64 = (x + y) % 250
nxt[z] = (nxt[z] + a) % MOD
}
y = y + 1
}
y = 0
while y < 250 {
arr[y] = nxt[y]
y = y + 1
}
i = i + 1
}
let mut ans: i64 = arr[0] - 1
if ans < 0 { ans = ans + MOD }
printf("%lld\n", ans)
free(arr); free(nxt)
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 modpow_i64_i64_i64(int64_t base, int64_t exp, int64_t mod);
int32_t main(void);
int64_t modpow_i64_i64_i64(int64_t base, int64_t exp, int64_t mod) {
int64_t r = 1;
int64_t b = FLOW_CHECKED_MOD((base), (mod));
int64_t e = exp;
while (e > 0) {
if (FLOW_CHECKED_MOD((e), (2)) == 1) {
r = FLOW_CHECKED_MOD(((r * b)), (mod));
}
b = FLOW_CHECKED_MOD(((b * b)), (mod));
e = FLOW_CHECKED_DIV((e), (2));
}
return r;
}
int32_t main(void) {
int64_t LIMIT = 250250;
int64_t MOD = 10000000000000000;
int64_t* arr = (int64_t*)(calloc(250, 8));
int64_t* nxt = (int64_t*)(calloc(250, 8));
if ((arr == NULL || nxt == NULL)) {
return 1;
}
arr[0] = 1;
int64_t i = 1;
while (i <= LIMIT) {
int64_t x = modpow_i64_i64_i64(i, i, 250);
int64_t y = 0;
while (y < 250) {
nxt[y] = 0;
y = (y + 1);
}
y = 0;
while (y < 250) {
int64_t a = arr[y];
if (a != 0) {
nxt[y] = FLOW_CHECKED_MOD(((nxt[y] + a)), (MOD));
int64_t z = FLOW_CHECKED_MOD(((x + y)), (250));
nxt[z] = FLOW_CHECKED_MOD(((nxt[z] + a)), (MOD));
}
y = (y + 1);
}
y = 0;
while (y < 250) {
arr[y] = nxt[y];
y = (y + 1);
}
i = (i + 1);
}
int64_t ans = (arr[0] - 1);
if (ans < 0) {
ans = (ans + MOD);
}
printf("%lld\n", ans);
free(arr);
free(nxt);
return 0;
}