# Project Euler 149
# Maximum-sum subsequence in a 2000×2000 lagged-Fibonacci matrix.
extern {
function calloc(n: i64, size: i64) -> ptr<void>
function free(p: ptr<void>) -> void
}
function max_sum(data: ptr<i64>, first: i64, last: i64, increment: i64) -> i64 {
let mut result: i64 = data[first]
let mut current: i64 = 0
let mut i: i64 = first
while i <= last {
current = current + data[i]
if current < 0 { current = 0 }
if result < current { result = current }
i = i + increment
}
return result
}
function main() -> i32 {
let size: i64 = 2000
let length: i64 = size * size
let data: ptr<i64> = calloc(length, 8)
if data == null { return 1 }
let mut k: i64 = 1
let mut idx: i64 = 0
while idx < 55 && idx < length {
let val: i64 = (100003 - 200003 * k + 300007 * k * k * k) % 1000000 - 500000
# fix negative mod
let mut v: i64 = (100003 - 200003 * k + 300007 * k * k * k) % 1000000
if v < 0 { v = v + 1000000 }
data[idx] = v - 500000
k = k + 1
idx = idx + 1
}
idx = 55
while idx < length {
let mut s: i64 = data[idx - 24] + data[idx - 55] + 1000000
s = s % 1000000
if s < 0 { s = s + 1000000 }
data[idx] = s - 500000
idx = idx + 1
}
let last: i64 = size - 1
let mut result: i64 = data[0]
let mut y: i64 = 0
while y < size {
let current: i64 = max_sum(data, y * size, y * size + last, 1)
if result < current { result = current }
y = y + 1
}
let mut x: i64 = 0
while x < size {
let current: i64 = max_sum(data, x, last * size + x, size)
if result < current { result = current }
x = x + 1
}
x = 0
while x < size {
let current: i64 = max_sum(data, x, (last - x) * size + last, size + 1)
if result < current { result = current }
x = x + 1
}
y = 1
while y < size {
let current: i64 = max_sum(data, y * size, last * size + (y), size + 1)
if result < current { result = current }
y = y + 1
}
x = 0
while x < size {
let current: i64 = max_sum(data, x, x * size, size - 1)
if result < current { result = current }
x = x + 1
}
y = 1
while y < size {
let current: i64 = max_sum(data, y * size + last, last * size + y, size - 1)
if result < current { result = current }
y = y + 1
}
printf("%lld\n", result)
free(data)
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 max_sum_ptr_i64_i64_i64_i64(int64_t* data, int64_t first, int64_t last, int64_t increment);
int32_t main(void);
int64_t max_sum_ptr_i64_i64_i64_i64(int64_t* data, int64_t first, int64_t last, int64_t increment) {
int64_t result = data[first];
int64_t current = 0;
int64_t i = first;
while (i <= last) {
current = (current + data[i]);
if (current < 0) {
current = 0;
}
if (result < current) {
result = current;
}
i = (i + increment);
}
return result;
}
int32_t main(void) {
int64_t size = 2000;
int64_t length = (size * size);
int64_t* data = (int64_t*)(calloc(length, 8));
if (data == NULL) {
return 1;
}
int64_t k = 1;
int64_t idx = 0;
while ((idx < 55 && idx < length)) {
int64_t val = (FLOW_CHECKED_MOD((((100003 - (200003 * k)) + (((300007 * k) * k) * k))), (1000000)) - 500000);
int64_t v = FLOW_CHECKED_MOD((((100003 - (200003 * k)) + (((300007 * k) * k) * k))), (1000000));
if (v < 0) {
v = (v + 1000000);
}
data[idx] = (v - 500000);
k = (k + 1);
idx = (idx + 1);
}
idx = 55;
while (idx < length) {
int64_t s = ((data[(idx - 24)] + data[(idx - 55)]) + 1000000);
s = FLOW_CHECKED_MOD((s), (1000000));
if (s < 0) {
s = (s + 1000000);
}
data[idx] = (s - 500000);
idx = (idx + 1);
}
int64_t last = (size - 1);
int64_t result = data[0];
int64_t y = 0;
while (y < size) {
int64_t current = max_sum_ptr_i64_i64_i64_i64(data, (y * size), ((y * size) + last), 1);
if (result < current) {
result = current;
}
y = (y + 1);
}
int64_t x = 0;
while (x < size) {
int64_t current = max_sum_ptr_i64_i64_i64_i64(data, x, ((last * size) + x), size);
if (result < current) {
result = current;
}
x = (x + 1);
}
x = 0;
while (x < size) {
int64_t current = max_sum_ptr_i64_i64_i64_i64(data, x, (((last - x) * size) + last), (size + 1));
if (result < current) {
result = current;
}
x = (x + 1);
}
y = 1;
while (y < size) {
int64_t current = max_sum_ptr_i64_i64_i64_i64(data, (y * size), ((last * size) + y), (size + 1));
if (result < current) {
result = current;
}
y = (y + 1);
}
x = 0;
while (x < size) {
int64_t current = max_sum_ptr_i64_i64_i64_i64(data, x, (x * size), (size - 1));
if (result < current) {
result = current;
}
x = (x + 1);
}
y = 1;
while (y < size) {
int64_t current = max_sum_ptr_i64_i64_i64_i64(data, ((y * size) + last), ((last * size) + y), (size - 1));
if (result < current) {
result = current;
}
y = (y + 1);
}
printf("%lld\n", result);
free(data);
return 0;
}