# Project Euler 194
# Last 8 digits of N(25,75,1984).
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 SA(c: i64) -> i64 {
return c*c*c*c*c - 9*c*c*c*c + 34*c*c*c - 69*c*c + 77*c - 38
}
function SB(c: i64) -> i64 {
return c*c*c*c*c - 8*c*c*c*c + 27*c*c*c - 50*c*c + 52*c - 24
}
function comb_mod(n: i64, k: i64, mod: i64) -> i64 {
# n! / (k! (n-k)!) mod mod; mod=1e8 not prime, so compute exactly with i128 then mod
let mut num: i128 = 1
let mut i: i64 = 0
while i < k {
num = num * ((n - i) as i128)
i = i + 1
num = num / (i as i128)
}
return (num % (mod as i128)) as i64
}
function main() -> i32 {
let MOD: i64 = 100000000
let a: i64 = 25
let b: i64 = 75
let c: i64 = 1984
let n: i64 = a + b
let comb: i64 = comb_mod(n, a, MOD)
let sa: i64 = ((SA(c) % MOD) + MOD) % MOD
let sb: i64 = ((SB(c) % MOD) + MOD) % MOD
let mut val: i64 = comb
val = (val * c) % MOD
val = (val * (c - 1)) % MOD
val = (val * modpow(sa, a, MOD)) % MOD
val = (val * modpow(sb, b, MOD)) % MOD
printf("%lld\n", val)
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);
int64_t SA_i64(int64_t c);
int64_t SB_i64(int64_t c);
int64_t comb_mod_i64_i64_i64(int64_t n, int64_t k, 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;
}
int64_t SA_i64(int64_t c) {
return (((((((((c * c) * c) * c) * c) - ((((9 * c) * c) * c) * c)) + (((34 * c) * c) * c)) - ((69 * c) * c)) + (77 * c)) - 38);
}
int64_t SB_i64(int64_t c) {
return (((((((((c * c) * c) * c) * c) - ((((8 * c) * c) * c) * c)) + (((27 * c) * c) * c)) - ((50 * c) * c)) + (52 * c)) - 24);
}
int64_t comb_mod_i64_i64_i64(int64_t n, int64_t k, int64_t mod) {
__int128 num = 1;
int64_t i = 0;
while (i < k) {
num = (num * ((__int128)((n - i))));
i = (i + 1);
num = FLOW_CHECKED_DIV((num), (((__int128)(i))));
}
return ((int64_t)(FLOW_CHECKED_MOD((num), (((__int128)(mod))))));
}
int32_t main(void) {
int64_t MOD = 100000000;
int64_t a = 25;
int64_t b = 75;
int64_t c = 1984;
int64_t n = (a + b);
int64_t comb = comb_mod_i64_i64_i64(n, a, MOD);
int64_t sa = FLOW_CHECKED_MOD(((FLOW_CHECKED_MOD((SA_i64(c)), (MOD)) + MOD)), (MOD));
int64_t sb = FLOW_CHECKED_MOD(((FLOW_CHECKED_MOD((SB_i64(c)), (MOD)) + MOD)), (MOD));
int64_t val = comb;
val = FLOW_CHECKED_MOD(((val * c)), (MOD));
val = FLOW_CHECKED_MOD(((val * (c - 1))), (MOD));
val = FLOW_CHECKED_MOD(((val * modpow_i64_i64_i64(sa, a, MOD))), (MOD));
val = FLOW_CHECKED_MOD(((val * modpow_i64_i64_i64(sb, b, MOD))), (MOD));
printf("%lld\n", val);
return 0;
}