int main(void)
{
unsigned abus[10000] = {0};
unsigned abuidx = 0;
unsigned i;
for (i=12;i<20162;i++) {
if (i < sum_of_divisors(i))
abus[abuidx++] = i;
}
unsigned numnums[20161] = {0};
for (i=0;i<20161;i++)
numnums[i] = (i+1);
unsigned j;
unsigned asum = 0;
for (i=0;i<abuidx;i++) {
for (j=0;j<abuidx;j++) {
asum = (abus[i] + abus[j]);
if (asum <= 20161)
numnums[asum-1] = 0;
}
}
unsigned tsum = 0;
for (i=0;i<20161;i++)
tsum += numnums[i];
printf("%u\n",tsum);
return 0;
}
int solve()
{
int abundant_map[LIMIT] = {0};
int map[LIMIT] = {0}; /* whether a num can be written as sum of abundant */
int i, j, ret;
/* prepare abundant-map */
for (i = 1; i < LIMIT; i++) {
if (sum_of_divisors(i) > 2*i) {
abundant_map[i] = 1;
}
}
for (i = 1; i < LIMIT / 2; i++) {
if (!abundant_map[i])
continue;
for (j = i; j < LIMIT && i + j < LIMIT; j++)
if (abundant_map[j])
map[i + j] = 1;
}
ret = 0;
for (i = 1; i < LIMIT; i++)
if (!map[i])
ret += i;
return ret;
}
int main(void)
{
clock_t start, end;
start = clock();
unsigned count=0, num_of_abundants=0, abundant_nums[LIMIT];
for(int n=1; n<LIMIT+1; n++){
if(sum_of_divisors(n) > n){
abundant_nums[num_of_abundants++] = n;
}
}
long unsigned total_sum = 0;
// by changing value at index i I mark the numbers not to count
int all_nums[LIMIT];
memset(all_nums, '\0', LIMIT);
for(int i=0; i<num_of_abundants; i++){
count = i;
while(abundant_nums[i] + abundant_nums[count] < LIMIT){
all_nums[abundant_nums[i] + abundant_nums[count]] = 1;
count++;
}
}
for (int j = 0; j < LIMIT; j++)
{
if(all_nums[j] != 1)
total_sum += j;
}
end = clock();
printf("Found: %lu \n", total_sum);
printf("Took me %f seconds to come up with a solution\n", ((end-start)/CLOCKS_PER_SEC)*1.0); // 0s :D
return 0;
}
int main() {
int i, j;
unsigned long long total = 0;
int* abundants = malloc(sizeof(int) * SIZE);
for (i = 0; i < SIZE; i++) abundants[i] = 0;
for (i=0;i<=SIZE;++i) {
if (sum_of_divisors(i) > i) {
abundants[i] = 1;
}
for (j=1;j<=i/2;++j) {
if (abundants[j] > 0 && abundants[i-j] > 0) {
total -= i;
break;
}
}
total += i;
}
free(abundants);
printf("%llu\n", total);
}
int main() {
short chain[SIZE];
int used[SIZE];
int used_length = 0, i, j, v, length, max_length, max_length_member;
for (i = 0; i < SIZE; i++) {
chain[i] = 0;
}
for (i = 1; i < SIZE; i++) {
for (j = 0; j < used_length; j++) {
//chain[used[j]] = 0;
}
used_length = 0;
v = i;
while (chain[v] == 0) {
chain[v] = 1;
used[used_length++] = v;
v = sum_of_divisors(v);
if (v > SIZE) {
used_length = 0;
break;
}
}
for (j = 0; j < used_length; j++) {
if (used[j] == v) {
length = used_length - j;
if (length > max_length) {
max_length = length;
max_length_member = used[j];
for (j = j + 1;j < used_length; j++) {
max_length_member = MIN(max_length_member, used[j]);
}
}
break;
}
}
}
printf("%d %d\n", max_length_member, max_length);
}
int main()
{
//printf("%d\n", solve());
printf("sum of divisors 12: %d\n", sum_of_divisors(12));
return 0;
}
