Submission #944937

#	Time	Username	Problem	Language	Result	Execution time	Memory
944937		sleepntsheep	Fancy Fence (CEOI20_fancyfence)	C11	100 / 100	23 ms	6348 KiB

fancyfence

#include<stdio.h>

#define N 100002
#define M 1000000007ll

int n,h[N],w[N],l[N],r[N];
long long pw[N],z;

long long c2(long long x){return (x-1)*x%M*500000004ll%M;}

long long c(long long ww,long long hh)
{
    ww%=M;
    hh%=M;
    return c2(ww+1)*c2(hh+1)%M;
}

void dfs(int u,int ll,int rr,int yy)
{
    if(!u||ll>rr)return;
    int y=h[u];
    long long ww=(pw[rr]-pw[ll-1])%M;
    z = (z + (c(ww,y) + M - c(ww,yy)) % M) % M;
    dfs(l[u],ll,u-1,y);
    dfs(r[u],u+1,rr,y);
}

int stk[N], top;

signed main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;++i)scanf("%d",h+i);
    for(int i=1;i<=n;++i)scanf("%d",w+i),pw[i]=pw[i-1]+w[i];

    for(int i=1;i<=n;++i)
    {
        int k=top;
        while(k&&h[stk[k]]>h[i])--k;
        if(k)r[stk[k]]=i;
        if(k<top)l[i]=stk[k+1];
        stk[++k]=i;
        top=k;
    }

    dfs(stk[1],1,n,0);
    printf("%lld",z);
}

Compilation message (stderr)

fancyfence.c: In function 'main':
fancyfence.c:32:5: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |     scanf("%d",&n);
      |     ^~~~~~~~~~~~~~
fancyfence.c:33:26: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     for(int i=1;i<=n;++i)scanf("%d",h+i);
      |                          ^~~~~~~~~~~~~~~
fancyfence.c:34:26: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |     for(int i=1;i<=n;++i)scanf("%d",w+i),pw[i]=pw[i-1]+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