# Project Euler 062
# Smallest cube for which exactly five permutations of its digits are cube.
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function digit_sig_into(n: i64, sigs: ptr<i8>, row: i32) -> void {
let cnt: ptr<i32> = calloc(10, 4)
if cnt == null { return }
let mut x: i64 = n
if x == 0 {
cnt[0] = 1
}
while x > 0 {
let d: i32 = (x % 10) as i32
cnt[d] = cnt[d] + 1
x = x / 10
}
let mut i: i32 = 0
while i < 10 {
sigs[row * 10 + i] = cnt[i] as i8
i = i + 1
}
free(cnt)
}
function sig_eq(sigs: ptr<i8>, a: i32, b: i32) -> bool {
let mut i: i32 = 0
while i < 10 {
if sigs[a * 10 + i] != sigs[b * 10 + i] { return false }
i = i + 1
}
return true
}
function num_digits(n: i64) -> i32 {
if n == 0 { return 1 }
let mut c: i32 = 0
let mut x: i64 = n
while x > 0 {
c = c + 1
x = x / 10
}
return c
}
function main() -> i32 {
let limit: i32 = 10000
let sigs: ptr<i8> = calloc((limit * 10) as i64, 1)
let cubes: ptr<i64> = calloc(limit as i64, 8)
let seen: ptr<i8> = calloc(limit as i64, 1)
if sigs == null || cubes == null || seen == null { return 1 }
let mut n: i32 = 1
while n < limit {
let ni: i64 = n as i64
let c: i64 = ni * ni * ni
cubes[n] = c
digit_sig_into(c, sigs, n)
n = n + 1
}
let mut ans: i64 = 0
let mut i: i32 = 1
while i < limit {
if seen[i] != 0 {
i = i + 1
continue
}
let digs_i: i32 = num_digits(cubes[i])
let mut cnt: i32 = 1
let mut j: i32 = i + 1
while j < limit {
let digs_j: i32 = num_digits(cubes[j])
if digs_j > digs_i { break }
if sig_eq(sigs, i, j) {
cnt = cnt + 1
seen[j] = 1
}
j = j + 1
}
seen[i] = 1
if cnt == 5 {
ans = cubes[i]
break
}
i = i + 1
}
printf("%lld\n", ans)
free(seen)
free(cubes)
free(sigs)
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; }
void digit_sig_into_i64_ptr_i8_i32(int64_t n, int8_t* sigs, int32_t row);
bool sig_eq_ptr_i8_i32_i32(int8_t* sigs, int32_t a, int32_t b);
int32_t num_digits_i64(int64_t n);
int32_t main(void);
void digit_sig_into_i64_ptr_i8_i32(int64_t n, int8_t* sigs, int32_t row) {
int32_t* cnt = (int32_t*)(calloc(10, 4));
if (cnt == NULL) {
return;
}
int64_t x = n;
if (x == 0) {
cnt[0] = 1;
}
while (x > 0) {
int32_t d = ((int32_t)(FLOW_CHECKED_MOD((x), (10))));
cnt[d] = (cnt[d] + 1);
x = FLOW_CHECKED_DIV((x), (10));
}
int32_t i = 0;
while (i < 10) {
sigs[((row * 10) + i)] = ((int8_t)(cnt[i]));
i = (i + 1);
}
free(cnt);
}
bool sig_eq_ptr_i8_i32_i32(int8_t* sigs, int32_t a, int32_t b) {
int32_t i = 0;
while (i < 10) {
if (sigs[((a * 10) + i)] != sigs[((b * 10) + i)]) {
return 0;
}
i = (i + 1);
}
return 1;
}
int32_t num_digits_i64(int64_t n) {
if (n == 0) {
return 1;
}
int32_t c = 0;
int64_t x = n;
while (x > 0) {
c = (c + 1);
x = FLOW_CHECKED_DIV((x), (10));
}
return c;
}
int32_t main(void) {
int32_t limit = 10000;
int8_t* sigs = (int8_t*)(calloc(((int64_t)((limit * 10))), 1));
int64_t* cubes = (int64_t*)(calloc(((int64_t)(limit)), 8));
int8_t* seen = (int8_t*)(calloc(((int64_t)(limit)), 1));
if (((sigs == NULL || cubes == NULL) || seen == NULL)) {
return 1;
}
int32_t n = 1;
while (n < limit) {
int64_t ni = ((int64_t)(n));
int64_t c = ((ni * ni) * ni);
cubes[n] = c;
digit_sig_into_i64_ptr_i8_i32(c, sigs, n);
n = (n + 1);
}
int64_t ans = 0;
int32_t i = 1;
while (i < limit) {
if (seen[i] != 0) {
i = (i + 1);
continue;
}
int32_t digs_i = num_digits_i64(cubes[i]);
int32_t cnt = 1;
int32_t j = (i + 1);
while (j < limit) {
int32_t digs_j = num_digits_i64(cubes[j]);
if (digs_j > digs_i) {
break;
}
if (sig_eq_ptr_i8_i32_i32(sigs, i, j)) {
cnt = (cnt + 1);
seen[j] = 1;
}
j = (j + 1);
}
seen[i] = 1;
if (cnt == 5) {
ans = cubes[i];
break;
}
i = (i + 1);
}
printf("%lld\n", ans);
free(seen);
free(cubes);
free(sigs);
return 0;
}