# Project Euler 092
# How many starting numbers below ten million arrive at 89 in square-digit chain.
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function sqdig(n: i32) -> i32 {
let mut s: i32 = 0
let mut x: i32 = n
while x > 0 {
let d: i32 = x % 10
s = s + d * d
x = x / 10
}
return s
}
function main() -> i32 {
# max sqdig sum for 9999999 is 7*81=567
let cache: ptr<i8> = calloc(600, 1)
if cache == null { return 1 }
# 0 = unknown, 1 = ends at 1, 2 = ends at 89
cache[1] = 1
cache[89] = 2
let mut i: i32 = 2
while i < 600 {
if cache[i] == 0 {
let mut x: i32 = i
while x != 1 && x != 89 && cache[x] == 0 {
x = sqdig(x)
}
let end: i8 = 1
if x == 89 || cache[x] == 2 {
end = 2
}
# fill chain
x = i
while x != 1 && x != 89 && cache[x] == 0 {
cache[x] = end
x = sqdig(x)
}
}
i = i + 1
}
let mut count: i64 = 0
let mut n: i32 = 1
while n < 10000000 {
let s: i32 = sqdig(n)
if cache[s] == 2 {
count = count + 1
}
n = n + 1
}
printf("%lld\n", count)
free(cache)
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 sqdig_i32(int32_t n);
int32_t main(void);
int32_t sqdig_i32(int32_t n) {
int32_t s = 0;
int32_t x = n;
while (x > 0) {
int32_t d = FLOW_CHECKED_MOD((x), (10));
s = (s + (d * d));
x = FLOW_CHECKED_DIV((x), (10));
}
return s;
}
int32_t main(void) {
int8_t* cache = (int8_t*)(calloc(600, 1));
if (cache == NULL) {
return 1;
}
cache[1] = 1;
cache[89] = 2;
int32_t i = 2;
while (i < 600) {
if (cache[i] == 0) {
int32_t x = i;
while (((x != 1 && x != 89) && cache[x] == 0)) {
x = sqdig_i32(x);
}
int8_t end = 1;
if ((x == 89 || cache[x] == 2)) {
end = 2;
}
x = i;
while (((x != 1 && x != 89) && cache[x] == 0)) {
cache[x] = end;
x = sqdig_i32(x);
}
}
i = (i + 1);
}
int64_t count = 0;
int32_t n = 1;
while (n < 10000000) {
int32_t s = sqdig_i32(n);
if (cache[s] == 2) {
count = (count + 1);
}
n = (n + 1);
}
printf("%lld\n", count);
free(cache);
return 0;
}