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C. Boats Competition codeforces

暴力 双指针

ac代码:

#include<iostream>
#include<algorithm>
#include<iomanip>
#include<set>
#include<queue>
#include<stack>
#include<vector>
#include<map>
#include<string.h>
#include<string>
#include<math.h>
#define INF 0x7fffffff
#define IOS; {ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);}
#define debug(x) {cout<<"<<<<"<<(x)<<endl;}
#define print(x) {cout<<(x)<<endl;} 
const int N = 50;
typedef long long ll;
using namespace std;
int gcd(int a,int b)
{return b==0?a:gcd(b,b%a);} 
int a[N];
int main() {
	IOS;
	int t;cin>>t;
	while(t--)
	{
		int n;cin>>n;
		for(int i=1;i<=n;i++)cin>>a[i];
		sort(a+1,a+1+n);
		int ans=0;
		for(int i=2;i<=2*n;i++)
		{
			int cnt=0;
			int l=1;
			int r=n;
			while(l<r)//暴力枚举 双指针 
			{
				if(a[l]+a[r]==i)
				{
					l++;r--;
					cnt++;	
				}	
				else if(a[l]+a[r]<i)
				{
					l++;
				}
				else r--; 
			}	
			ans=max(ans,cnt);
		} 
		cout<<ans<<endl;
	} 
	return 0;
}
	

本文标签: 指针暴力Boatscompetition