wikioi1180 模拟
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#include<cstdio>
#include<cstring>
#include <algorithm>
#include <iostream>
#define SUM(x) (x+n)
using namespace std;
int n,b,k,num[50000],sum[50000],lft[100000],rht[100000],ans;
int main()
{
while(~scanf("%d%d",&n,&b))
{
ans=0;
memset(num,0,sizeof(num));
memset(sum,0,sizeof(sum));
memset(lft,0,sizeof(lft));
memset(rht,0,sizeof(rht));
for(int i=1;i<=n;i++)
{
scanf("%d",&num[i]);
if(num[i]==b)
{
k=i;
num[i]=0;
}
else num[i]=num[i]>b?1:-1;
}
lft[SUM(0)]=rht[SUM(0)]=1;
for(int i=k-1;i>=1;i--)
{
sum[i]=sum[i+1]+num[i];
lft[SUM(sum[i])]++;
}
for(int i=k+1;i<=n;i++)
{
sum[i]=sum[i-1]+num[i];
rht[SUM(sum[i])]++;
}
for(int i=1-n;i<=n-1;i++)
ans+=lft[SUM(i)]*rht[(n<<1)-SUM(i)];
printf("%d\n",ans);
}
return 0;
}
#include<cstring>
#include <algorithm>
#include <iostream>
#define SUM(x) (x+n)
using namespace std;
int n,b,k,num[50000],sum[50000],lft[100000],rht[100000],ans;
int main()
{
while(~scanf("%d%d",&n,&b))
{
ans=0;
memset(num,0,sizeof(num));
memset(sum,0,sizeof(sum));
memset(lft,0,sizeof(lft));
memset(rht,0,sizeof(rht));
for(int i=1;i<=n;i++)
{
scanf("%d",&num[i]);
if(num[i]==b)
{
k=i;
num[i]=0;
}
else num[i]=num[i]>b?1:-1;
}
lft[SUM(0)]=rht[SUM(0)]=1;
for(int i=k-1;i>=1;i--)
{
sum[i]=sum[i+1]+num[i];
lft[SUM(sum[i])]++;
}
for(int i=k+1;i<=n;i++)
{
sum[i]=sum[i-1]+num[i];
rht[SUM(sum[i])]++;
}
for(int i=1-n;i<=n-1;i++)
ans+=lft[SUM(i)]*rht[(n<<1)-SUM(i)];
printf("%d\n",ans);
}
return 0;
}
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