Codeforces Gym 101190 NEERC 2016 B. Binary Code

题解

#include<bits/stdc++.h>using namespace std;#define N 500010#define M 4000000vector<char>c[N];vector<int>a[N<<1],g[M];int num,nx[N<<1][2],w[N<<1],w2[N<<1];int i,j,k,n,m,p,pos[N],pr[N<<1],sf[N<<1],l;int Rt=1;char s[N];inline void Insert(int& x,int y,int z){    if(!x)x=++num;    if(y==l){        a[x].push_back(z);        return;    }    Insert(nx[x][s[y]-'0'],y+1,z);}inline void Build(int x,int y,int z){    if(!x)return;    int X=++num,Y=++num;    if(a[x].size()==0){        pr[x]=X;sf[x]=Y;    }else{        pr[x]=++num;sf[x]=++num;        for(int i=0;i<a[x].size();i++){            w[a[x][i]]=++num;            g[num].push_back(a[x][i]^1);            if(!i)g[pr[x]].push_back(num);else g[w[a[x][i-1]]].push_back(num);            if(i==(int)a[x].size()-1)g[num].push_back(X);            w2[a[x][i]]=++num;g[num].push_back(a[x][i]^1);        }        for(int i=0;i<a[x].size();i++){            if(i==(int)a[x].size()-1)g[Y].push_back(w2[a[x][i]]),g[a[x][i]].push_back(X);            else g[a[x][i]].push_back(w[a[x][i+1]]),g[w2[a[x][i+1]]].push_back(w2[a[x][i]]);            if(!i)g[w2[a[x][i]]].push_back(sf[x]),g[a[x][i]].push_back(sf[x]);else g[a[x][i]].push_back(w2[a[x][i-1]]);        }    }    if(y)g[y].push_back(pr[x]),g[sf[x]].push_back(z);    Build(nx[x][0],X,Y);Build(nx[x][1],X,Y);}bool b[M];int cnt;int f[M],dfn[M],low[M],T,st[M],top;inline void Dfs(int x){    dfn[x]=low[x]=++T;st[++top]=x;    for(int i=0;i<g[x].size();i++){        int v=g[x][i];        if(!dfn[v])Dfs(v),low[x]=min(low[x],low[v]);else        if(!f[v])low[x]=min(low[x],dfn[v]);    }    if(low[x]==dfn[x]){        ++cnt;        while(st[top]!=x)f[st[top--]]=cnt;        f[st[top--]]=cnt;    }}inline bool Tarjan(){    for(int i=2;i<=num;i++)    if(!dfn[i])Dfs(i);    for(int i=1;i<=n;i++)    if(f[i<<1]==f[i<<1|1])return 0;    return 1;}int main(){    freopen("binary.in","r",stdin);    freopen("binary.out","w",stdout);    scanf("%d",&n);    memset(pos,-1,sizeof(pos));num=n<<1|1;    for(i=1;i<=n;i++){        scanf("%s",s);l=strlen(s);        for(j=0;j<l;j++){            if(s[j]=='?')pos[i]=j;            c[i].push_back(s[j]);        }        if(pos[i]==-1)Insert(Rt,0,i<<1|1),g[i<<1].push_back(i<<1|1);else{            s[pos[i]]='0';Insert(Rt,0,i<<1|1);            s[pos[i]]='1';Insert(Rt,0,i<<1);        }    }    Build(1,0,0);    if(!Tarjan())puts("NO");else{        puts("YES");        for(i=1;i<=n;i++){            for(j=0;j<c[i].size();j++)            if(c[i][j]=='?')putchar((f[i<<1]<f[i<<1|1])+'0');else putchar(c[i][j]);            putchar('\n');        }    }    return 0;}