Codeforces Round #616 (Div. 1) C Prefix Enlightenment

带权并查集

#include
#define LL long long
#define PB push_back
using namespace std;
const int INF=0x3f3f3f3f;
const int N=1e6+10,M=N*400,mod=1e9+7;
int a[N];
int s[N][2];
int d[N];
int n,k;
int ans;
vector<int>G[N];
int typ[N];
int p[N];
int f(int x){
    if(x==a[x])return x;
    int y=a[x];
    a[x]=f(a[x]);
    d[x]=(d[x]+d[y])%2;
    return a[x];
}
int main()
{
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++)scanf("%1d",&p[i]);
    for(int i=1;i<=k;i++)a[i]=i,s[i][0]=1,typ[i]=-1;
    ans=0;
    for(int i=1,m,x;i<=k;i++){
        scanf("%d",&m);
        for(int j=1;j<=m;j++){
            scanf("%d",&x);
            G[x].PB(i);
        }
    }
    for(int i=1,x,y,u,v;i<=n;i++){
        if(G[i].size()==1){
            x=G[i][0];
            y=f(x);
            if(typ[y]==-1){
                ans-=min(s[y][0],s[y][1]);
                if((d[x]+(!p[i]))%2)typ[y]=1,swap(s[y][0],s[y][1]),ans+=s[y][1];
                else typ[y]=0,ans+=s[y][1];
            }
        }
        else if(G[i].size()==2){
            x=G[i][0],y=G[i][1];
            u=f(x),v=f(y);
            if(u!=v){
                if(typ[u]==-1)ans-=min(s[u][0],s[u][1]);
                else ans-=s[u][1];
                if(typ[v]==-1)ans-=min(s[v][0],s[v][1]);
                else ans-=s[v][1];
                a[u]=v;
                d[u]=(d[x]+d[y]+(!p[i]))%2;
                if(typ[v]!=-1&&typ[u]==-1){
                    typ[u]=(typ[v]+d[u])%2;
                    if(typ[u]==1)swap(s[u][0],s[u][1]);
                }
                if(typ[u]!=-1&&typ[v]==-1){
                    typ[v]=(typ[u]+d[u])%2;
                    if(typ[v]==1)swap(s[v][0],s[v][1]);
                }
                if(typ[u]!=-1)s[v][0]+=s[u][0],s[v][1]+=s[u][1];
                else s[v][0]+=s[u][d[u]],s[v][1]+=s[u][!d[u]];
                if(typ[v]==-1)ans+=min(s[v][0],s[v][1]);
                else ans+=s[v][1];
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}
/*
*/