注意不要重复计数就ok了,奉上java满分代码
import java.util.Scanner;
public class Main {
public static void main(String[] args){
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
int[] numArr = new int[n];
for(int i = 0; i < n; i++){
numArr[i] = scanner.nextInt();
}
scanner.close();
int count = 0;
for(int i = 0; i < n; i++){
int numI = numArr[i];
for(int j = i + 1; j < n; j++){
if(numArr[j] + numI == 0){
count++;
break;
}
}
}
System.out.println(count);
}
}