Codeforces Mail.Ru Cup 2018 Round 2

A. Metro

#include<cstdio>
int main(){
	int n,s;
	int a[1005],b[1005];	
	while(~scanf("%d%d",&n,&s)){
		int k=0;
		for(int i=0;i<n;i++)
		scanf("%d",&a[i]);
		for(int i=0;i<n;i++)
		scanf("%d",&b[i]);
		if(a[0]==0)
		printf("NO\n");
		else if(a[s-1]==1)
		printf("YES\n");
		
		else {
			for(int i=s;i<n;i++){
			if(a[i]==1&&b[i]==1)
			k++;
		}
			if(k>0&&b[s-1]==1)
			printf("YES\n");
			else printf("NO\n");
		}
		
	}
}

B. Alice and Hairdresser

#include<cstdio>
const int maxn=1e5+5;
long long a[maxn]={0};
int main(){
	int n,m,l,count=0;
	scanf("%d%d%d",&n,&m,&l);
	for(int i=1;i<=n;i++){
		scanf("%d",&a[i]);
		if(a[i-1]<=l&&a[i]>l)
		count++;
	}
	int q,p,d;
	for(int i=0;i<m;i++){
		scanf("%d",&q);
		if(q==0)
		printf("%d\n",count);
		else{
			scanf("%d%d",&p,&d);
				if(a[p]<=l&&(a[p]+d)>l){
					if(a[p-1]<=l&&a[p+1]<=l)
					count++;
				else if(a[p-1]>l&&a[p+1]>l)
					count--;	
				}
			a[p]+=d;
		}
	}
}

C. Lucky Days

#include<cstdio>
#include<algorithm>
using namespace std;
int gcd(int a,int b){
	if(b!=0)
	return gcd(b,a%b);
	else return a;
}
int main(){
	int l1,r1,t1,l2,r2,t2;
	scanf("%d%d%d",&l1,&r1,&t1);
	scanf("%d%d%d",&l2,&r2,&t2);
		int g=gcd(max(t1,t2),min(t1,t2));
		int len1=r1-l1+1;
		int len2=r2-l2+1;
		l1%=g;
		l2%=g;
		int p=0,ans=0;
		p=min(l1+len1,l2+len2)-max(l1,l2);
		ans=max(p,ans);
		if(l1<l2)
		l1+=g;
		else l2+=g;
		p=min(l1+len1,l2+len2)-max(l1,l2);
		ans=max(p,ans);
		printf("%d\n",ans);
	
}