CF813F Bipartite Checking（lct，同bzoj4025）

动态加边删边，判断是否是二分图。同bzoj4025

#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
#define N 100010
#define pa pair
inline char gc(){
    static char buf[1<<16],*S,*T;
    if(S==T){T=(S=buf)+fread(buf,1,1<<16,stdin);if(T==S) return EOF;}
    return *S++;
}
inline int read(){
    int x=0,f=1;char ch=gc();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=gc();}
    while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=gc();
    return x*f;
}
int n,Q,m=0,fa[N<<1],c[N<<1][2],sz[N<<1],v[N<<1],mn[N<<1],cnt=0,q[N<<1];
bool rev[N<<1];int mark[N];
struct quer{
    int op,id;
}qq[N];
struct edge{
    int x,y;
}e[N];
mapint>mp;
inline bool isroot(int x){return x!=c[fa[x]][0]&&x!=c[fa[x]][1];}
inline void update(int p){
    int l=c[p][0],r=c[p][1];
    sz[p]=sz[l]+sz[r]+1;
    if(v[p]<=v[mn[l]]&&v[p]<=v[mn[r]]) mn[p]=p;
    else if(v[mn[l]]<=v[mn[r]]) mn[p]=mn[l];else mn[p]=mn[r];
}
inline void pushdown(int p){
    if(!rev[p]) return;rev[p]=0;swap(c[p][0],c[p][1]);
    rev[c[p][0]]^=1;rev[c[p][1]]^=1;
}
inline void rotate(int x){
    int y=fa[x],z=fa[y],l=x==c[y][1],r=l^1;
    if(!isroot(y)) c[z][y==c[z][1]]=x;
    fa[c[x][r]]=y;fa[y]=x;fa[x]=z;
    c[y][l]=c[x][r];c[x][r]=y;update(y);update(x);
}
inline void splay(int x){
    int top=0;q[++top]=x;
    for(int xx=x;!isroot(xx);xx=fa[xx]) q[++top]=fa[xx];
    while(top) pushdown(q[top--]);
    while(!isroot(x)){
        int y=fa[x],z=fa[y];
        if(!isroot(y)){
            if(x==c[y][1]^y==c[z][1]) rotate(x);
            else rotate(y);
        }rotate(x);
    }
}
inline void access(int x){
    int y=0;while(x){splay(x);c[x][1]=y;update(x);y=x;x=fa[x];}
}
inline void makeroot(int x){
    access(x);splay(x);rev[x]^=1;
}
inline void link(int x,int y){
    makeroot(x);fa[x]=y;
}
inline void cut(int x,int y){
    makeroot(x);access(y);splay(y);c[y][0]=fa[x]=0;update(y);
}
inline int qmin(int x,int y){
    makeroot(x);access(y);splay(y);return mn[y];
}
inline int find(int x){
    access(x);splay(x);while(c[x][0]) x=c[x][0];return x;
}
int main(){
//  freopen("a.in","r",stdin);
    n=read();Q=read();mn[0]=0;v[0]=inf;
    for(int i=1;i<=Q;++i){
        int x=read(),y=read();if(x>y) swap(x,y);
        int id=mp[make_pair(x,y)];
        if(id) qq[i].op=0,qq[i].id=id,mp[make_pair(x,y)]=0,v[n+id]=i;
        else qq[i].op=1,qq[i].id=++m,e[m].x=x,e[m].y=y,mp[make_pair(x,y)]=m;
    }for(int i=1;i<=n;++i) v[i]=inf,mn[i]=i;
    for(int i=1;i<=m;++i){if(!v[n+i]) v[n+i]=Q+1;mn[n+i]=n+i;}
    for(int i=1;i<=Q;++i){
        int id=qq[i].id,x=e[id].x,y=e[id].y;
        if(qq[i].op){
            if(find(x)!=find(y)) link(x,id+n),link(id+n,y);
            else{
                makeroot(x);access(y);splay(y);
                if(sz[y]-1>>1&1){//偶环
                    int z=qmin(x,y);if(v[id+n]<=v[z]) mark[id]=2;
                    else mark[z-n]=2,cut(e[z-n].x,z),cut(e[z-n].y,z),link(x,id+n),link(id+n,y);
                }else{//奇环
                    int z=qmin(x,y);++cnt;if(v[id+n]<=v[z]) mark[id]=1;
                    else mark[z-n]=1,cut(e[z-n].x,z),cut(e[z-n].y,z),link(x,id+n),link(id+n,y);
                }
            }
        }else{
            if(!mark[id]) cut(x,id+n),cut(id+n,y);
            else if(mark[id]==1) --cnt;
        }puts(cnt?"NO":"YES");
    }return 0;
}