比b小的设为-1，大的设为1，前缀和搞一下就行了

#include
      
       #include
       
        #include
        
         #include
         
           #include
          
           #define ll long long using namespace std;const int maxn=500010,inf=1e9;int n,b,x,pos;int a[maxn],v[maxn];ll ans;void read(int &k){    int f=1;k=0;char c=getchar();    while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar();    while(c<='9'&&c>='0')k=k*10+c-'0',c=getchar();    k*=f;}int main(){    read(n);read(b);    for(int i=1;i<=n;i++)    {        read(x);        if(x
           
            b)a[i]=1; else a[i]=0,pos=i; a[i]+=a[i-1]; } for(int i=0;i