晴问-寻找元素对

暴力

n=int(input())
a=list(map(int,input().split()))
target=int(input())
count=0
for i in range(n):
    for j in range(i+1,n):
        if(a[i]+a[j]==target):
            count+=1
print(count)

#include <cstdio>
const int maxn=100;
int a[maxn];
int main(){
    int n,target;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%d",&a[i]);
    }
    scanf("%d",&target);
    int count=0;
    for(int i=0;i<n;i++){
        for(int j=i+1;j<n;j++){
            if(a[i]+a[j]==target){
                count++;
            }
        }
    }
    printf("%d",count);
    return 0;
}