BZOJ 2288 贪心 +链表

 思路：

放个题解好吧.

http://www.cnblogs.com/zyfzyf/p/4114774.html

 

//By SiriusRen
#include <queue>
#include <cstdio>
#include <algorithm>
using namespace std;
const int N=100050;
int a[N],s[N],top,n,m,add,minu,tot,next[N],pre[N],vis[N];
struct Node{int v,id;Node(){}Node(int x,int y){v=x,id=y;}};
bool operator<(Node a,Node b){return a.v>b.v;}
priority_queue<Node>pq;
long long ans;
signed main(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        if(a[i]>0){
            add+=a[i];
            if(minu&&top)s[++top]=minu;
            minu=0;
        }
        else if(a[i]<0){
            minu+=a[i];
            if(add)s[++top]=add;
            add=0;
        }
    }
    if(add)s[++top]=add;
    for(int i=1;i<=top;i++){
        if(s[i]>0)pq.push(Node(s[i],i)),tot++,ans+=s[i];
        else pq.push(Node(-s[i],i)),s[i]=-s[i];
        next[i]=i+1,pre[i]=i-1;
    }next[top]=0;
    if(tot<=m){
        printf("%d\n",ans);
        return 0;
    }
    else{
        for(int i=1;i<=tot-m;i++){
            Node tp=pq.top();pq.pop();
            while(vis[tp.id]&&!pq.empty())
                tp=pq.top(),pq.pop();
            if(vis[tp.id])break;
            ans-=tp.v;
            if(pq.empty())break;
            int x=tp.id;
            if(!pre[x]){
                vis[next[x]]=vis[x]=1;pre[next[next[x]]]=0;
            }
            else if(!next[x]){
                vis[x]=vis[pre[x]]=1;next[pre[pre[x]]]=0;
            }
            else{
                vis[pre[x]]=vis[next[x]]=1;
                tp.v=s[x]=s[pre[x]]+s[next[x]]-s[x];
                if(next[next[x]])pre[next[next[x]]]=x;
                if(pre[pre[x]])next[pre[pre[x]]]=x;
                pre[x]=pre[pre[x]];next[x]=next[next[x]];
                pq.push(tp);
            }
        }
        printf("%d\n",ans);
    }
}

 

//By SiriusRen

#include <queue>

#include <cstdio>

#include <algorithm>

using namespace std;

const int N=100050;

int a[N],s[N],top,n,m,add,minu,tot,next[N],pre[N],vis[N];

struct Node{int v,id;Node(){}Node(int x,int y){v=x,id=y;}};

bool operator<(Node a,Node b){return a.v>b.v;}

priority_queue<Node>pq;

long long ans;

signed main(){

    scanf("%d%d",&n,&m);

    for(int i=1;i<=n;i++){

        scanf("%d",&a[i]);

        if(a[i]>0){

            add+=a[i];

            if(minu&&top)s[++top]=minu;

            minu=0;

        }

        else if(a[i]<0){

            minu+=a[i];

            if(add)s[++top]=add;

            add=0;

        }

    }

    if(add)s[++top]=add;

    for(int i=1;i<=top;i++){

        if(s[i]>0)pq.push(Node(s[i],i)),tot++,ans+=s[i];

        else pq.push(Node(-s[i],i)),s[i]=-s[i];

        next[i]=i+1,pre[i]=i-1;

    }next[top]=0;

    if(tot<=m){

        printf("%d\n",ans);

        return 0;

    }

    else{

        for(int i=1;i<=tot-m;i++){

//          for(int j=1;j<=top;j++)printf("%d ",next[j]);puts("");

//          printf("ans=%d\n",ans);

            Node tp=pq.top();pq.pop();

            while(vis[tp.id]&&!pq.empty())

                tp=pq.top(),pq.pop();

            if(vis[tp.id])break;

            ans-=tp.v;

//          printf("v=%d\n",tp.v);

            if(pq.empty())break;

            int x=tp.id;

            if(!pre[x]){

                vis[next[x]]=vis[x]=1;pre[next[next[x]]]=0;

            }

            else if(!next[x]){

                vis[x]=vis[pre[x]]=1;next[pre[pre[x]]]=0;

            }

            else{

                vis[pre[x]]=vis[next[x]]=1;

                tp.v=s[x]=s[pre[x]]+s[next[x]]-s[x];

                if(next[next[x]])pre[next[next[x]]]=x;

                if(pre[pre[x]])next[pre[pre[x]]]=x;

                pre[x]=pre[pre[x]];next[x]=next[next[x]];

                pq.push(tp);

            }

//          for(int j=1;j<=top;j++)printf("%d ",next[j]);puts("");

        }

        printf("%d\n",ans);

    }

}