# Project Euler 159
# Sum of maximum digital root sums of factorisations for n = 2..999999.
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function digit_root(x0: i64) -> i32 {
let mut x: i64 = x0
while x >= 10 {
let mut s: i64 = 0
while x > 0 {
s = s + (x % 10)
x = x / 10
}
x = s
}
return x as i32
}
function main() -> i32 {
let limit: i64 = 999999
let mdrs: ptr<i32> = calloc(limit + 1, 4)
if mdrs == null { return 1 }
let mut i: i64 = 2
while i <= limit {
mdrs[i] = digit_root(i)
i = i + 1
}
let mut a: i64 = 2
while a <= limit {
let mut b: i64 = 2
while a * b <= limit && b <= a {
let prod: i64 = a * b
let cand: i32 = mdrs[a] + mdrs[b]
if mdrs[prod] < cand {
mdrs[prod] = cand
}
b = b + 1
}
a = a + 1
}
let mut total: i64 = 0
i = 2
while i <= limit {
total = total + (mdrs[i] as i64)
i = i + 1
}
printf("%lld\n", total)
free(mdrs)
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 digit_root_i64(int64_t x0);
int32_t main(void);
int32_t digit_root_i64(int64_t x0) {
int64_t x = x0;
while (x >= 10) {
int64_t s = 0;
while (x > 0) {
s = (s + FLOW_CHECKED_MOD((x), (10)));
x = FLOW_CHECKED_DIV((x), (10));
}
x = s;
}
return ((int32_t)(x));
}
int32_t main(void) {
int64_t limit = 999999;
int32_t* mdrs = (int32_t*)(calloc((limit + 1), 4));
if (mdrs == NULL) {
return 1;
}
int64_t i = 2;
while (i <= limit) {
mdrs[i] = digit_root_i64(i);
i = (i + 1);
}
int64_t a = 2;
while (a <= limit) {
int64_t b = 2;
while (((a * b) <= limit && b <= a)) {
int64_t prod = (a * b);
int32_t cand = (mdrs[a] + mdrs[b]);
if (mdrs[prod] < cand) {
mdrs[prod] = cand;
}
b = (b + 1);
}
a = (a + 1);
}
int64_t total = 0;
i = 2;
while (i <= limit) {
total = (total + ((int64_t)(mdrs[i])));
i = (i + 1);
}
printf("%lld\n", total);
free(mdrs);
return 0;
}