题解 | 牛牛学数列
牛牛学数列
https://www.nowcoder.com/practice/0b97367cd2184c12a0e02f7c223aee11
import java.util.Scanner;
//奇数正，偶数负
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int a = in.nextInt();
int sum = 0;
for (int i = 0; i <= a; i++) {
if (i % 2 == 0) {
sum -= i;
}
else sum += i;
}
System.out.println(sum);
}
}
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