# Project Euler 013
# First ten digits of the sum of one hundred 50-digit numbers.
# Digit-array addition — expressive and still native-speed.
extern {
function fopen(path: string, mode: string) -> ptr<void>
function fgetc(f: ptr<void>) -> i32
function fclose(f: ptr<void>) -> i32
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function main() -> i32 {
# sum digits, least-significant first; allow carry room
let sum: ptr<i32> = calloc(60, 4)
if sum == null {
return 1
}
let f: ptr<void> = fopen("data/p013.txt", "r")
if f == null {
printf("failed to read data/p013.txt\n")
free(sum)
return 1
}
let mut line: ptr<i32> = calloc(50, 4)
let mut c: i32 = fgetc(f)
while c >= 0 {
let mut len: i32 = 0
while c >= 0 && c != 10 {
if c >= 48 && c <= 57 {
line[len] = c - 48
len = len + 1
}
c = fgetc(f)
}
if len == 50 {
let mut i: i32 = 0
while i < 50 {
sum[i] = sum[i] + line[49 - i]
i = i + 1
}
}
if c == 10 {
c = fgetc(f)
}
}
fclose(f)
free(line)
# propagate carry
let mut i: i32 = 0
while i < 59 {
sum[i + 1] = sum[i + 1] + sum[i] / 10
sum[i] = sum[i] % 10
i = i + 1
}
# find most-significant non-zero digit
let mut top: i32 = 59
while top > 0 && sum[top] == 0 {
top = top - 1
}
let mut result: i64 = 0
let mut k: i32 = 0
while k < 10 {
result = result * 10 + (sum[top - k] as i64)
k = k + 1
}
printf("%lld\n", result)
free(sum)
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 main(void);
int32_t main(void) {
int32_t* sum = (int32_t*)(calloc(60, 4));
if (sum == NULL) {
return 1;
}
void* f = (void*)(fopen("data/p013.txt", "r"));
if (f == NULL) {
printf("failed to read data/p013.txt\n");
free(sum);
return 1;
}
int32_t* line = (int32_t*)(calloc(50, 4));
int32_t c = fgetc(f);
while (c >= 0) {
int32_t len = 0;
while ((c >= 0 && c != 10)) {
if ((c >= 48 && c <= 57)) {
line[len] = (c - 48);
len = (len + 1);
}
c = fgetc(f);
}
if (len == 50) {
int32_t i = 0;
while (i < 50) {
sum[i] = (sum[i] + line[(49 - i)]);
i = (i + 1);
}
}
if (c == 10) {
c = fgetc(f);
}
}
fclose(f);
free(line);
int32_t i = 0;
while (i < 59) {
sum[(i + 1)] = (sum[(i + 1)] + FLOW_CHECKED_DIV((sum[i]), (10)));
sum[i] = FLOW_CHECKED_MOD((sum[i]), (10));
i = (i + 1);
}
int32_t top = 59;
while ((top > 0 && sum[top] == 0)) {
top = (top - 1);
}
int64_t result = 0;
int32_t k = 0;
while (k < 10) {
result = ((result * 10) + ((int64_t)(sum[(top - k)])));
k = (k + 1);
}
printf("%lld\n", result);
free(sum);
return 0;
}