# Project Euler 242
# Odd triplets count for n <= 10^12.
function pow3(m: i32) -> i64 {
let mut r: i64 = 1
let mut i: i32 = 0
while i < m {
r = r * 3
i = i + 1
}
return r
}
function bit_length(t: i64) -> i32 {
if t == 0 { return 0 }
let mut n: i64 = t
let mut m: i32 = 0
while n > 0 {
n = n / 2
m = m + 1
}
return m
}
function prefix_sum_pow2_popcount(t0: i64) -> i64 {
if t0 < 0 { return 0 }
let mut res: i64 = 0
let mut mult: i64 = 1
let mut t: i64 = t0
while true {
if t == 0 {
res = res + mult
break
}
let m: i32 = bit_length(t) - 1
let p: i64 = 1
let mut i: i32 = 0
while i < m {
p = p * 2
i = i + 1
}
if t == p - 1 {
res = res + mult * pow3(m)
break
}
res = res + mult * pow3(m)
t = t - p
mult = mult * 2
}
return res
}
function main() -> i32 {
let n_max: i64 = 1000000000000
let t_max: i64 = (n_max - 1) / 4
printf("%lld\n", prefix_sum_pow2_popcount(t_max))
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 pow3_i32(int32_t m);
int32_t bit_length_i64(int64_t t);
int64_t prefix_sum_pow2_popcount_i64(int64_t t0);
int32_t main(void);
int64_t pow3_i32(int32_t m) {
int64_t r = 1;
int32_t i = 0;
while (i < m) {
r = (r * 3);
i = (i + 1);
}
return r;
}
int32_t bit_length_i64(int64_t t) {
if (t == 0) {
return 0;
}
int64_t n = t;
int32_t m = 0;
while (n > 0) {
n = FLOW_CHECKED_DIV((n), (2));
m = (m + 1);
}
return m;
}
int64_t prefix_sum_pow2_popcount_i64(int64_t t0) {
if (t0 < 0) {
return 0;
}
int64_t res = 0;
int64_t mult = 1;
int64_t t = t0;
while (1) {
if (t == 0) {
res = (res + mult);
break;
}
int32_t m = (bit_length_i64(t) - 1);
int64_t p = 1;
int32_t i = 0;
while (i < m) {
p = (p * 2);
i = (i + 1);
}
if (t == (p - 1)) {
res = (res + (mult * pow3_i32(m)));
break;
}
res = (res + (mult * pow3_i32(m)));
t = (t - p);
mult = (mult * 2);
}
return res;
}
int32_t main(void) {
int64_t n_max = 1000000000000;
int64_t t_max = FLOW_CHECKED_DIV(((n_max - 1)), (4));
printf("%lld\n", prefix_sum_pow2_popcount_i64(t_max));
return 0;
}