BZOJ1786: [Ahoi2008]Pair 配对/1831: [AHOI2008]逆序对

#include<cstring>
#include<iostream>
#include<cstdio>
#include<map>
#include<cmath>
#include<algorithm>
#define rep(i,l,r) for (int i=l;i<=r;i++)
#define down(i,l,r) for (int i=l;i>=r;i--)
#define clr(x,y) memset(x,y,sizeof(x))
#define low(x) (x&(-x)) 
#define maxn 10050
#define inf 2000000000
#define mm 1000000007
using namespace std;
int f[maxn][105],a[maxn],t[maxn],pos[maxn],c[maxn][105];
int now,n,k,cnt,ans;
int read(){
    int x=0,f=1; char ch=getchar();
    while (!isdigit(ch)) {if (ch==‘-‘) f=-1; ch=getchar();}
    while (isdigit(ch)) {x=x*10+ch-‘0‘; ch=getchar();}
    return x*f;
}
void add(int x,int y){
    while (x<=k){
        t[x]=t[x]+y;
        x+=low(x);
    }
}
int ask(int x){
    int ans=0;
    while (x){
        ans+=t[x];
        x-=low(x);
    }
    return ans;
}
int main(){
    n=read(); k=read();
    rep(i,1,n){
        a[i]=read(); 
        if (a[i]!=-1){
            ans+=ask(k)-ask(a[i]); add(a[i],1);
        }
        else {
            pos[++cnt]=i;
            rep(j,1,k) c[i][j]+=ask(k)-ask(j);
        }
    }
    clr(t,0);
    down(i,n,1){
        if (a[i]!=-1) add(a[i],1);  
        else {
            rep(j,1,k) c[i][j]+=ask(j-1);
        }
    }
    rep(i,1,cnt) rep(j,0,k) f[i][j]=inf;
    rep(i,1,cnt){
        int now=pos[i];
        rep(j,1,k) f[i][j]=min(f[i][j-1],f[i-1][j]+c[now][j]);
    }
    printf("%d\n",f[cnt][k]+ans);
    return 0;
}