Pascal(fpc 3.0.2) 解法, 执行用时: 4ms, 内存消耗: 256K, 提交时间: 2019-04-17 21:10:22

var
n,i,j,k:integer;
a,b:array[1..101] of integer; begin
readln(n);
fillchar(b,sizeof(b),0);
for i:=1 to n do read(a[i]);
for i:=1 to n do
for j:=1 to n do
for k:=j+1 to n do
if a[i]=a[j]+a[k] then b[i]:=1; k:=0;
for i:=1 to n do
if b[i]=1 then k:=k+1;
writeln(k);
end.

C++11(clang++ 3.9) 解法, 执行用时: 3ms, 内存消耗: 484K, 提交时间: 2018-09-23 09:33:55

#include<iostream>
using namespace std;
int main()
{
	int a[105]={0},h[20005]={0},i,j,s=0,n;
	cin>>n;
	for(i=1;i<=n;i++)cin>>a[i];
	for(i=1;i<=n;i++)
	for(j=i+1;j<=n;j++)
	{
	h[a[i]+a[j]]++;
	}
	for(i=1;i<=n;i++)if(h[a[i]]!=0)s++;
	cout<<s;
}

Python3(3.5.2) 解法, 执行用时: 44ms, 内存消耗: 3916K, 提交时间: 2019-08-27 09:51:25

n=input()
a=list(map(int,input().split()))
print(len(set(a)&set([i+j for i in a for j in a if i!=j])))