「日常训练」Divisibility by Eight（Codeforces Round 306 Div.2 C）

题意与分析

极简单的数论+思维题。

代码

#include <bits/stdc++.h>
#define MP make_pair
#define PB emplace_back
#define fi first
#define se second
#define ZERO(x) memset((x), 0, sizeof(x))
#define ALL(x) (x).begin(),(x).end()
#define rep(i, a, b) for (repType i = (a); i <= (b); ++i)
#define per(i, a, b) for (repType i = (a); i >= (b); --i)
#define QUICKIO                  \
    ios::sync_with_stdio(false); \
    cin.tie(0);                  \
    cout.tie(0);
using namespace std;
using ll=long long;
using repType=int;

bool judge(int x)
{
	if(x%8==0)
	{
		cout<<"YES"<<endl<<x<<endl;
		return true;
	}
	return false;
}

bool judge(int x,int y)
{
	if(judge(x) || judge(y) || judge(x*10+y)) return true;
	return false;
}

int main()
{
	string str; cin>>str;
	if(str.length()<=2)
	{
		if(str.length()==1)
		{
			if((str[0]-'0')%8) cout<<"NO"<<endl;
			else
			{
				cout<<"YES"<<endl<<str<<endl;
			}
			return 0;
		}
		else
		{
			if((str[0]-'0')%8==0)
			{
				cout<<"YES"<<endl<<str[0]<<endl;
				return 0;
			}
			else if((str[1]-'0')%8==0)
			{
				cout<<"YES"<<endl<<str[1]<<endl;
				return 0;
			}
			else if(((str[1]-'0')*10+str[0]-'0')%8==0)
			{
				cout<<"YES"<<endl<<str<<endl;
				return 0;
			}
			cout<<"NO"<<endl;
			return 0;
		}
	}
	rep(i,0,str.length()-3)
	{
		int x=str[i]-'0';
		if(judge(x)) return 0;
		rep(j,i+1,str.length()-2)
		{
			int y=str[j]-'0';
			if(judge(y) || judge(x,y)) return 0;
			rep(k,j+1,str.length()-1)
			{
				int z=str[k]-'0';
				if(judge(z) || judge(x,z) || judge(y,z)) return 0;
				if(z%2) continue;
				//cout<<x<<" "<<y<<" "<<z<<endl;
				//cout<<(!(x%2))<<" "<<(y*10+z)%8<<((!(x%2)) && (y*10+z)%8==4)<<endl;
				if((!(x%2) && (y*10+z)%8==0) || (x%2 && (y*10+z)%8==4))
				{
					cout<<"YES"<<endl;
					//cout<<i<<" "<<j<<" "<<k<<endl;
					rep(p,0,str.length()-1)
					{
						//cout<<"("<<p<<") ";
						if(p<i || p==i || p==j || p==k) cout<<str[p];
					}
					cout<<endl;
					return 0;
				}
			}
		}
	}
	cout<<"NO"<<endl;
	return 0;
}