XJOI网上同步测试DAY14 T1

思路:线段树维护最短路

#include<cstdio>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<cstring>
struct node{
     int l,r,c[3][3];
}t[1000005];
int id[3][400005];
int s[3][400005];
int fa[400005],n;
int read(){
    int t=0,f=1;char ch=getchar();
    while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}
    while ('0'<=ch&&ch<='9'){t=t*10+ch-'0';ch=getchar();}
    return t*f;
}
int find(int x){
     if (fa[x]==x) return x;
         else return fa[x]=find(fa[x]);
}
node operator +(node a,node b){
     node p;
     p.l=std::min(a.l,b.l);
     p.r=std::max(a.r,b.r);
     p.c[0][0]=p.c[1][1]=p.c[0][1]=p.c[1][0]=0x3f3f3f3f;
     for (int i=0;i<=1;i++)
        if (s[i][a.l]==0) 
        for (int j=0;j<=1;j++)
            if (s[j][b.r]==0)
            for (int k=0;k<=1;k++)
                if (s[k][a.r]==0&&s[k][b.l]==0)
                    p.c[i][j]=std::min(p.c[i][j],a.c[i][k]+b.c[k][j]+1);
                    
     return p;                
}
void build(int k,int l,int r){
    t[k].c[0][0]=t[k].c[1][1]=t[k].c[1][0]=t[k].c[0][1]=0x3f3f3f3f;
    if (l==r){
        t[k].l=t[k].r=l;
        if (s[0][l]==0) t[k].c[0][0]=0;
        if (s[1][l]==0) t[k].c[1][1]=0;
        if (s[0][l]==0&&s[1][l]==0) t[k].c[0][1]=t[k].c[1][0]=1;
        return;
    }
    int mid=(l+r)>>1;
    build(k*2,l,mid);
    build(k*2+1,mid+1,r);
    t[k]=t[k*2]+t[k*2+1];
}
void init(){
    char S[400005];
    scanf("%s",S+1);
    for (int i=1;i<=n;i++)
        s[0][i]=S[i]-'0';
    scanf("%s",S+1);    
    for (int i=1;i<=n;i++)
        s[1][i]=S[i]-'0';
    int sz=0;
    for (int i=0;i<2;i++)
        for (int j=1;j<=n;j++)
            id[i][j]=++sz;
    for (int i=1;i<=2*n;i++) fa[i]=i;        
    for (int i=1;i<n;i++)
        if (s[0][i]==0&&s[0][i+1]==0) fa[find(id[0][i])]=find(id[0][i+1]);
    for (int i=1;i<n;i++)
        if (s[1][i]==0&&s[1][i+1]==0) fa[find(id[1][i])]=find(id[1][i+1]);
    for (int i=1;i<=n;i++)
        if (s[0][i]==0&&s[1][i]==0) fa[find(id[1][i])]=find(id[0][i]);        
    
}
node query(int k,int l,int r,int x,int y){
    int mid=(l+r)>>1;
    node tmp;
    if (l==x&&r==y) return t[k];
    if (y<=mid) return query(k*2,l,mid,x,y);
    else
    if (x>mid) return query(k*2+1,mid+1,r,x,y);
    else return query(k*2,l,mid,x,mid)+query(k*2+1,mid+1,r,mid+1,y);
}
int main(){
    int T;
    n=read();T=read();
    init();
    build(1,1,n);    
    while (T--){
        int x=read(),y=read();
        if (x==y) {puts("0");continue;}
        if (find(x)!=find(y)){puts("You have been confusional!");continue;}
        int x1=(x>n)?x-n:x;int y1=(y>n)?y-n:y;
        if (x1>y1) std::swap(x,y),std::swap(x1,y1);
        node tmp=query(1,1,n,x1,y1);
        int id1,id2;
        if (x>n) id1=1;else id1=0;
        if (y>n) id2=1;else id2=0;
        int ans=tmp.c[id1][id2];
        if (ans==0x3f3f3f3f) puts("You have been confusional!");
        else printf("%d\n",ans);    
    }    
}