Project Euler Problem 12
The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be:
1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
Let us list the factors of the first seven triangle numbers:
1: 1
3: 1,3
6: 1,2,3,6
10: 1,2,5,10
15: 1,3,5,15
21: 1,3,7,21
28: 1,2,4,7,14,28
We can see that 28 is the first triangle number to have over five divisors.
What is the value of the first triangle number to have over five hundred divisors?
1 #include <iostream>
2 using namespace std;
3
4 int GetDivisorsCount(long long num)
5 {
6 if(num < 1)
7 {
8 return 1;
9 }
10
11 int count = 1;
12 int factor = 2;
13 long long n = num;
14 int i, t;
15 while(n > 1)
16 {
17 if(n % factor == 0)
18 {
19 t = 1;
20 while(n % factor == 0)
21 {
22 t++;
23 n /= factor;
24 }
25 count *= t;
26 }
27 factor++;
28 }
29
30 return count;
31 }
32
33 int main()
34 {
35 long long sum = 0;
36 long long i = 1;
37 while(GetDivisorsCount(sum) < 500)
38 {
39 sum = sum + i++;
40 cout << sum << endl;
41 }
42
43 cout << sum;
44 cin.get();
45 }
2 using namespace std;
3
4 int GetDivisorsCount(long long num)
5 {
6 if(num < 1)
7 {
8 return 1;
9 }
10
11 int count = 1;
12 int factor = 2;
13 long long n = num;
14 int i, t;
15 while(n > 1)
16 {
17 if(n % factor == 0)
18 {
19 t = 1;
20 while(n % factor == 0)
21 {
22 t++;
23 n /= factor;
24 }
25 count *= t;
26 }
27 factor++;
28 }
29
30 return count;
31 }
32
33 int main()
34 {
35 long long sum = 0;
36 long long i = 1;
37 while(GetDivisorsCount(sum) < 500)
38 {
39 sum = sum + i++;
40 cout << sum << endl;
41 }
42
43 cout << sum;
44 cin.get();
45 }
