sgu105-数学

105. Div 3 time limit per test: 0.25 sec.  memory limit per test: 4096 KB There is sequence 1, 12, 123, 1234, ..., 12345678910, ... . Given first N elements of that sequence. You must determine amount of numbers in it that are divisible by 3. Input Input contains N (1<=N<=231 - 1). Output Write answer to the output. Sample Input 4 Sample Output 2 我是根据发现规律解出来的 1 0 2 1 3 2 4 2 5 3 6 4 7 4 8 5 9 6 10 6 11 7 12 8 #include <iostream> using namespace std; int main() { int N; cin >> N; int ans = 0; if (N % 3 == 2) ans++; ans += 2 * (N / 3); cout << ans; return 0; }