CF1111C Creative Snap 线段树

用线段树模拟一下就好了~

code:

#include <cstdio>
#include <algorithm>
#define lson ls[x]
#define rson rs[x]
#define N 10000006
#define ll long long
#define setIO(s) freopen(s".in","r",stdin)
using namespace std;
ll A,B;
int n,k,tot;
int ls[N],rs[N],sum[N];
void update(int &x,int l,int r,int p)
{
    if(!x) x=++tot;
    ++sum[x];
    if(l==r) return;
    int mid=(l+r)>>1;
    if(p<=mid)  update(lson,l,mid,p);
    else update(rson,mid+1,r,p);
}
ll query(int x,int l,int r)
{
    if(!x) return A;
    if(l==r) return B*sum[x];
    int mid=(l+r)>>1;
    ll re=B*1ll*(r-l+1)*sum[x];
    return min(re,query(lson,l,mid)+query(rson,mid+1,r));
}
int main()
{
    // setIO("input");
    int i,j,bs=1,rt=0;
    scanf("%d%d%lld%lld",&n,&k,&A,&B);
    for(i=1;i<=n;++i)  bs<<=1;
    for(i=1;i<=k;++i)
    {
        int po;
        scanf("%d",&po),update(rt,1,bs,po);
    }
    printf("%lld\n",query(rt,1,bs));
    return 0;
}