# Project Euler 081
# Minimal path sum in matrix moving only right and down.
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 read_int(f: ptr<void>) -> i32 {
let mut c: i32 = fgetc(f)
while c >= 0 && (c < 48 || c > 57) {
c = fgetc(f)
}
if c < 0 { return -1 }
let mut v: i32 = 0
while c >= 48 && c <= 57 {
v = v * 10 + (c - 48)
c = fgetc(f)
}
return v
}
function min2(a: i64, b: i64) -> i64 {
if a < b { return a }
return b
}
function main() -> i32 {
let n: i32 = 80
let a: ptr<i64> = calloc((n * n) as i64, 8)
if a == null { return 1 }
let f: ptr<void> = fopen("data/p081.txt", "r")
if f == null {
printf("failed to read data/p081.txt\n")
free(a)
return 1
}
let mut i: i32 = 0
while i < n * n {
a[i] = read_int(f) as i64
i = i + 1
}
fclose(f)
let mut r: i32 = 0
while r < n {
let mut c: i32 = 0
while c < n {
if r == 0 && c == 0 {
# start
} elif r == 0 {
a[c] = a[c] + a[c - 1]
} elif c == 0 {
a[r * n] = a[r * n] + a[(r - 1) * n]
} else {
a[r * n + c] = a[r * n + c] + min2(a[(r - 1) * n + c], a[r * n + c - 1])
}
c = c + 1
}
r = r + 1
}
printf("%lld\n", a[n * n - 1])
free(a)
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 read_int_ptr_void(void* f);
int64_t min2_i64_i64(int64_t a, int64_t b);
int32_t main(void);
int32_t read_int_ptr_void(void* f) {
int32_t c = fgetc(f);
while ((c >= 0 && (c < 48 || c > 57))) {
c = fgetc(f);
}
if (c < 0) {
return (-1);
}
int32_t v = 0;
while ((c >= 48 && c <= 57)) {
v = ((v * 10) + (c - 48));
c = fgetc(f);
}
return v;
}
int64_t min2_i64_i64(int64_t a, int64_t b) {
if (a < b) {
return a;
}
return b;
}
int32_t main(void) {
int32_t n = 80;
int64_t* a = (int64_t*)(calloc(((int64_t)((n * n))), 8));
if (a == NULL) {
return 1;
}
void* f = (void*)(fopen("data/p081.txt", "r"));
if (f == NULL) {
printf("failed to read data/p081.txt\n");
free(a);
return 1;
}
int32_t i = 0;
while (i < (n * n)) {
a[i] = ((int64_t)(read_int_ptr_void(f)));
i = (i + 1);
}
fclose(f);
int32_t r = 0;
while (r < n) {
int32_t c = 0;
while (c < n) {
if ((r == 0 && c == 0)) {
} else if (r == 0) {
a[c] = (a[c] + a[(c - 1)]);
} else if (c == 0) {
a[(r * n)] = (a[(r * n)] + a[((r - 1) * n)]);
} else {
a[((r * n) + c)] = (a[((r * n) + c)] + min2_i64_i64(a[(((r - 1) * n) + c)], a[(((r * n) + c) - 1)]));
}
c = (c + 1);
}
r = (r + 1);
}
printf("%lld\n", a[((n * n) - 1)]);
free(a);
return 0;
}