题解 | #等差数列#
等差数列
https://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
#include <iostream> using namespace std; int main() { int x; cin >> x; int result = ((2 + 2 +3 * (x-1))*x/2); cout << result; }
直接掏公式
等差数列
https://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
#include <iostream> using namespace std; int main() { int x; cin >> x; int result = ((2 + 2 +3 * (x-1))*x/2); cout << result; }
直接掏公式
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