Codeforces Round #512 (Div. 2, based on Technocup 2019 Elimination Round 1)

传送门：http://codeforces.com/contest/1058

A.水题

#include<bits/stdc++.h>
int main()
{
	int n,flag=0,a;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		scanf("%d",&a);
		if(a==1)flag=10;
	}
	if(flag==10)printf("HARD");
	else printf("EASY");
	return 0;
}

B.计算几何：把图画出来分类讨论，把解析式写出来。

#include<bits/stdc++.h>
using namespace std;
#define maxn 100+10
int main()
{
	int d,n,m,x,y;
	scanf("%d%d%d",&n,&d,&m);

	int y1,y2;
	for(int i=1;i<=m;i++)
	{
		scanf("%d %d",&x,&y);
	if(d<=n-d)
	{
			if(x<=d)
		{
			y1=x+d;
			y2=-x+d;
			//cout<<y1<<y2<<endl;
			if(y<=y1&&y>=y2)printf("YES");
			else printf("NO");
		}
		else if(x<=(n-d)&&x>d)
		{
			y1=x+d;
			y2=x-d;
			if(y<=y1&&y>=y2)printf("YES");
			else printf("NO");	
		}
		else if(x>(n-d)&&x<=n)
		{
			y1=-x-d+2*n;
			y2=x-d;
			if(y<=y1&&y>=y2)printf("YES");
			else printf("NO");	
		}
		else printf("NO");
		printf("\n");
	}
	else 
	{
		if(x<=n-d)
		{
			y1=x+d;
			y2=-x+d;
			//cout<<y1<<y2<<endl;
			if(y<=y1&&y>=y2)printf("YES");
			else printf("NO");
		}
		else if(x<=d&&x>(n-d))
		{
			y1=-x-d+2*n;
			y2=-x+d;
			//cout<<y1<<y2<<endl;
			if(y<=y1&&y>=y2)printf("YES");
			else printf("NO");	
		}
		else if(x>d&&x<=n)
		{
			y1=-x-d+2*n;
			y2=x-d;
			//cout<<y1<<y2<<endl;
			if(y<=y1&&y>=y2)printf("YES");
			else printf("NO");	
		}
		else printf("NO");
		printf("\n");
	}
	}
   return 0;
}

C.暴力搞一搞

#include<bits/stdc++.h>
using namespace std;
int n,i,j,x,y,flag;
char s[102];
int main(){
	scanf("%d%s",&n,s);
	for (i=0;i<n-1;i++)
	{
		x+=s[i]-'0';
		y=0;
		flag=0;
		for (j=i+1;j<n;j++)
		{
			y+=s[j]-'0';
			if (y==x) y=0,flag=1;
			else if (y>x) break;
		}
		if (!y && flag)
		{
			puts("YES");
			return 0;
		}
	}
	puts("NO");
}

D.