今天明确了2-SAT;

表示对一对整数之间的关系是否存在

#include<cstdio>

#include<algorithm>

#include<iostream>

#include<cstring>

#include<map>

using namespace std;

const int Maxn = 1e5+10;

int mark[Maxn  << 1];

int s[Maxn * 2],top,tp;

int head[Maxn*2];

map <int,int> mp;

int x[Maxn * 2];

struct  {

    int v,next;

}E[Maxn << 2];

void init(){

    memset(head,-1,sizeof(head));

    memset(E,-1,sizeof(E));

    tp = 0;

}

int n,m,a,b;

void addedge(int u,int v){

    E[tp].v = v;

    E[tp].next = head[u];

    head[u] = tp++;

}

bool dfs(int x){

    if(mark[x^1])return false;

    if(mark[x])return true;

    mark[x] = true;

    s[top++] = x;

    for(int i=head[x];i!=-1;i=E[i].next){

        int v = E[i].v;

        if(!dfs(v))return false;

    }

    return true;

}

bool solve(){

    for(int i=0;i<n*2;i+=2){

        if(!mark[i] && !mark[i+1]){

            top = 0;

            if(!dfs(i)){

                while(top > 0)mark[s[--top]] = false;

                if(!dfs(i+1)) return false;

            }

        }

    }

    return true;

}

int main(){

    init();

    cin >> n >> a >> b;

    for(int i = 1;i<= n;i++){

        scanf("%d",&x[i]);

        mp[x[i]] = i;

    }

    for(int i=1;i<=n;i++){

        int val = x[i],s = i;

        s--;

        int t = mp[a - val];t--;

        if(!mp[a-val])addedge(2*s,2*s+1);

        else {

            addedge(2*s,2*t);

            addedge(2*t+1,2*s+1);

        }

         t=mp[b-val]; t--;

            if(!mp[b-val])

                addedge(2*s+1,2*s);

            else{

                addedge(2*s+1,2*t+1);

                addedge(2*t,2*s);

            }

    }

    if(!solve()){

        puts("NO");

    }

    else {

        printf("YES\n");

        for(int i=0;i<2*n;i+=2){

            if(i!=0)

                printf(" ");

            if(mark[i])

                printf("0");

            else

                printf("1");

        }

        printf("\n");

    }

}