Submission #291192

#	Time	Username	Problem	Language	Result	Execution time	Memory
291192		TadijaSebez	Fancy Fence (CEOI20_fancyfence)	C++11	100 / 100	43 ms	1916 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int mod=1e9+7;
int add(int x,int y){x+=y;return x>=mod?x-mod:x;}
void ckadd(int&x,int y){x=add(x,y);}
int sub(int x,int y){x-=y;return x<0?x+mod:x;}
void cksub(int&x,int y){x=sub(x,y);}
int mul(int x,int y){return (ll)x*y%mod;}
int C2(int x){return (ll)x*(x+1)/2%mod;}
const int N=100050;
int h[N],w[N],H[N],W[N],c;
int main(){
	int n;
	scanf("%i",&n);
	for(int i=1;i<=n;i++)scanf("%i",&h[i]);
	for(int i=1;i<=n;i++)scanf("%i",&w[i]);
	int sum=0,ans=0;
	for(int i=1;i<=n;i++){
		int sum_w=0;
		while(c>0&&H[c]>=h[i]){
			ckadd(sum_w,W[c]);
			cksub(sum,mul(C2(H[c]),W[c]));
			c--;
		}
		ckadd(ans,mul(w[i],add(sum,mul(sum_w,C2(h[i])))));
		ckadd(ans,mul(C2(w[i]),C2(h[i])));
		ckadd(sum_w,w[i]);
		ckadd(sum,mul(sum_w,C2(h[i])));
		c++;H[c]=h[i];W[c]=sum_w;
	}
	printf("%i\n",ans);
	return 0;
}

Compilation message (stderr)

fancyfence.cpp: In function 'int main()':
fancyfence.cpp:15:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   15 |  scanf("%i",&n);
      |  ~~~~~^~~~~~~~~
fancyfence.cpp:16:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   16 |  for(int i=1;i<=n;i++)scanf("%i",&h[i]);
      |                       ~~~~~^~~~~~~~~~~~
fancyfence.cpp:17:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |  for(int i=1;i<=n;i++)scanf("%i",&w[i]);
      |                       ~~~~~^~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 18 / 18
• Subtask 7: 27 / 27